OP, Let me state this constructively but in the strongest possible terms:
This project is heading for BIG TROUBLE. If you can get that broken stud out, then I support what Dittmer is saying. LEAVE the rest alone! You go trying to get that manifold off to take it to a machine shop, etc. the odds are WAY against you getting all EIGHT manifold bolts out. There's a case right now where one of our OP's found two broken exhaust manifold bolts. Worked about a week and ended up pulling the head to go to a shop. That led to a valve job, bolt hole oversize, etc.
Part of why I'm saying this, is the amount of rust I'm seeing in the picture. Being in New England where they salt the roads. Rhode Island where the air can be humid and salty.
Our OP brought a mechanic to the RV and he couldn't get the broken bolts out of the head. Find somebody who specializes in stuck bolts and broken tools (like Drills, Taps, Easy Outs), hopefully mobile. You've got big cities up there, somebody's got to be doing this.
If RV has do go to a shop, see if you can wrap the area in something that'll keep it from burning the area and drive it. If they can't come to you, and you can't drive it to them, disconnect the driveshaft and have it towed.
This thing has got me scared.
