I travel a lot, quite cheaply, with a backpack and camera bag, never have a car, and am almost always traveling alone. So, I have a few ideas here.
-Would not recommend South America, but there's a qualification. Love it, but it's quite difficult without Spanish (or (Portuguese). I find the people who don't speak Spanish end up only talking to other tourists (and most were not traveling alone to begin with). I'm not sure I can agree with johnnywalker that it's "not a problem," although more popular countries like Peru will have more English speakers. HOWEVER--if you have 6 months to spare and want to choose a few places to LEARN Spanish, it will give you a great excuse to stay in one city/town for a month or so, and then the basis of language for the next few months. I'd definitely recommend Colombia as a great country for this. You can study in a high-energy city like Medellin for a few weeks, then move somewhere remote and laidback and off-the-beaten track like Mompos for a few more weeks. I think they might have a Spanish school set up by now. Mompos would be a great place to work on documenting people. The Spanish is quite clear through the center of the country. Bolivia's Spanish is also on the slower side, and it's a ridiculously gorgeous country. If you were to do a longer cross-continental journey, generally it would probably be best to get your Spanish down in an Andean area before tackling the coasts ...or Argentina.
-Highly, highly, highly recommend the Middle East if you can. I went alone when I was 28 (turned 29 while there) and am a girl who looked 20 at the time. Did not feel in danger. Summer is damn hot, but it's dry heat and fewer tourists, and you could save the hotter countries for the second half of your six months. I only got to travel in the Middle East for 7.5 weeks, which I constantly regret...can only imagine how much I'd learn and what I would have seen with six months. I flew into Cairo and out of Istanbul and traveled only by public transportation in-between. Language is not a huge issue--I found more English speakers there than in South/Central America. It's eye-opening, as cliched as it might sound--as much as I love all my travels, there was just nothing quite as culturally impactful as this trip. I truly wish I had not been as nervous about photographing people as I was then...I wish I had a record of all the wonderful people I spoke with. For those of us in North America, the physical landscape alone is a huge change. Syria is still my absolute favorite country...would be happy staying for a month or more, rather than the measly 2 weeks I did.
-For specific countries that are absolutely overflowing with documentary possibilities, my recommendations are Ethiopia and Myanmar, both because of photogenic beauty, unique cultures, friendly people. (Friendlier in Myanmar--I admit some people hate Ethiopia but to me, it is fascinating in its energetic craziness). Amount of English speakers is probably similar in both. Unfortunately you're not departing at an ideal time of year for either one, but honestly...both so interesting. The advantage with Myanmar is that you could combine it with a longer trip to nearby countries. Whether it's a Southeast Asia trip or a South Asia trip, you have to fly into Myanmar either way (cannot cross the borders by land) so it doesn't really matter where you're coming from, but you could at least be nearby in the region. Still though--summer is not ideal. Do you have to leave in June?
As for costs, hosts, etc. I think Europe is too expensive, but your budget may tell you differently. Check couchsurfing.com or hospitalityclub.org. I used HC when I went to the Middle East. I don't really do it anymore as I have a job and am paid for my vacations, but it was great and I constantly meet people who love it. For the countries I've recommended, cheap lodging is easy to find anyway. I very rarely pay more than 10USD/night but my usual is closer to $6. My most ridiculous price was 86 cents on the Sinai Peninsula. Price basically depends on what you need, and really all I need is a bed. I prefer porcelain toilets but you take what you can get! For me, the lodging is the least important part of any trip, I'm there 8-10 hours a day at the most. The particular countries that intrigue me unfortunately often don't have good cuisines, so that budget goes down as well. If you want your trip to stretch out as long as possible, you can certainly save money without sacrificing enjoyment.
Oh, and for this type of travel, urban environment is definitely not necessary to be car-free. You can also simply choose a place that's small enough to walk around.
Can't really give recs on equipment, because I prefer 35mm.
Sorry this got so long...travel is obviously my biggest passion 
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