I would encourage you to check out a few other denominations then. AG is very missions oriented.
Also as an umbrella you can check out YWAM. There aren't any age requirements that I'm aware of, but I'm not yet 30 so possibly I overlooked them. As with any mission group though, you have to keep in mind your own belief system...be open to new revelation but closed to things that don't line up with your spirit. There are certain things in YWAM I'm pretty on the fence about...some of that involves becoming well versed in the religion of that particular country.
My brother got invited to a Ramadan feast in YWAM and called and asked if he should go. I'll leave that to your own discretion and personally I see NO reason why you would need to understand their religion to that extent unless you feel STRONGLY that is how the Lord wants you to be used, and of course to spend a lot of time in prayer about it.
I will note that it was not "required".
He is currently overseas for like 2-3 months. His total start up was around 5k for a 6 month program. To me that's not unreasonable.
MOST of the cost of mission trips is airfare. That's why short terms are so expensive. If you extend it to 6 weeks+ it's not any more expensive than day to day costs beyond the initial airfare...in fact sometimes it can be cheaper.
I haven't ever heard of a mission trip like what you have described. I would have some words to say with that organization. Tons of info I can provide. I'm thinking about it myself and found a place in Peru that I can go that has housing and is $500/mo. for as long as you feel led to stay (of course airfare not included
)
I do feel you on your own backyard being a mission but America is so unlike most places in the world. Doing ministry in the church is all well and good but I want to lead someone to Jesus and the soil isn't fertile here it seems. I've just had so many doors slammed in my face. People already "know"...
If you feel like this is your mission field and that's what the Lord wants...WOOOHOOO!
To answer the OP though on how do you know. I'm not sure at present. I know that I went when I was 16 and loved it more than anything I've ever done. We did street ministry (human videos, tracts, worship, and convo) and these people owned a coffee shop that was just a meeting place. People shared their testimonies. Usual stuff.
I did recall a man that was like a street-wise and now knowing more or less what I'm like the memories I have of people just off that one trip is helpful in realizing there are many styles and it takes all types. I was also encouraged by a guy that led small groups when I was like 14 that also went on it and he wouldn't hang out with our "group" when we were on buses and stuff. He would strike up conversations with locals and thinking back that's exactly what I do...maybe a soil softener? Except I don't see that in scripture unless possibly it's tilling. Not sure.
So yeah, I know I like it, but I didn't want to go back until I was sure it was the Lord. I'm still not, but am seriously considering it once again because I want to start from the ground up with people that haven't ever heard. Plant churches and just do ministry work in areas where it's like an answered prayer to people. I have had dreams about talking to missionaries but I take dreams with a grain of salt.
Getting a bit long (as per usual alas) but usually you have to reach out on your own if you want to not participate in "christian tourism" and actually want to do "missions". So like look through AG, Baptist, Church of God missionaries that they support. Reach out to one of the missionaries and plan a trip and state your intentions of why you don't really want to go on a church sponsored one and ask them about your concerns. On your own there is far less red tape. You just need a passport and a visa I think if you are staying past a certain amount of time. I'm sure they'd meet you at the airport and apprise you of places you shouldn't really go to for safety reasons.
Honestly if you have a heart for the lost going and living with a missionary for a bit is a great way to talk about that. In my experience, other than new believers that are passionate, people don't have a burden for evangelism that becomes a lifestyle. That burning desire and urgency only comes from the Lord though and not everyone has it that way.
There are also sub focuses of missions. Like a church building trip (for people that like to build), Well-digging trips, Optometry trips, Dentistry trips. Gardening/farming is very much in need in a lot of these places.
Sooo many of them are 2 week and are basically vacations with a smattering of ministry outreaches. It's a good way to get a feel for whether or not you like being in another country though, and to perceive a need. Kind of like a simulation.
Well alright...finishing up! I promise. In the end, I don't think there's any harm to going on one, other than confusion if you feel torn like I do about where to be when I see multiple needs. There are low cost alternatives like Alaska or Mexico...you can take a bus to mexico.
Thanks for bring up the topic...got me to flesh out some of the things I've been feeling about it. I always wanted to have a church on a hillside in some remote country far removed from America but that was too picture perfect so I just shrugged it off and focused on what was here. I am rethinking my position ha.
Edit: took a gander at another post. I disagree with the money just spontaneously appearing. It "can". But you could also work for a year and save 10% to be used for that purpose. Paul was self funded for the most part...the others were not. Just something to consider. I've not gone because the money didn't come through and I was like "well why can't I work a job for it" No reason you can't. Unless someone shows me the money thing in the word I don't consider that a signal.