A few things to consider. And yes I read you other thread too.
1. You're planning on full timing in this and not for recreational purposes (primarily). Class Bs and Sprinter conversions are very small. Not great bang for the buck for someone who's parking it. (Although you did allude to stealth camping it, so if that's the case then a white Sprinter with no windows is the most incognito, lol).
2. Most class C's are **** near the same from a mechanical standpoint.
You have a traditional Ford or Chevy V8 or a Ford V10. All are about as reliable as any Ford or Chevy pickup. Concentrate on floorplan, price, size and your credit issue, not ease of wrenching on them. No clear advantages or disadvantages to any of them and frankly some things are more accessible with a doghouse than a traditional truck front clip.
3. You don't say what you have for a vehicle, and your "budget" and wants/needs is kinda scattered. But, presume you need a vehicle for transportation and a RV to live in. And it's not like you're chock full of resources and tools if you're in an apartment/RV. AND you said your ultimate setup is a 5th wheel. I'd be much more inclined to get a TT or 5ver and a truck, than a motorhome. Mohos are better suited for people on the road all the time with their RV. If that's you, great. If not, a truck and trailer are one less drivetrain to own or maintain.
4. Cost. Sounds like you're doing ok, but not wiping your @ss with dollar bills. A new RV will depreciate more than a used one. Any RV will deteriorate and or show obvious signs of use being parked outside 24/7 and lived in full time. No sense in buying brand new just to have your 5 year old RV be worth less than someone elses 10-15 year old rv that's been covered and lightly used, 5 years from now.
5. Build some credit. Doing the apartment thing, you could buy a (used) truck now, on credit, and then buy a trailer in a little while. I think TTs and 5vers generally depreciate more than motor homes, so better value (if you have/need the truck anyway). And if you get a big HD truck, you might find a cheaper older TC that you could spring for with cash if you jsut gotta get out of the apartment. If you have $0 for downpayments etc going into this, it's not going to be pretty regardless of which path you choose.
Or to sum it up, best value is get a big pickup and then you can get any type of trailer you want. Get a cheap throwaway for the short term, build credit with a truck loan, still have a large living area and not spend much on the fist RV. $10k for a trailer will get you a very nice trailer and you'll have the configuration (a full truck hood) that you started the thread with.