I have a 16 x 2.75" sava tire and garelli wheel on the back of my puch and a 24" x 1.5"? bicycle rim/tire up front.
To do the wide rear wheel, you need to modify the rear swing arm because the inside gets very narrow where it meets the body (I imagine it's probably more difficult if you have a rigid frame).
It's disigned sort of like a V <-where the bottom of the v meets with the bike. You need to turn it into more of a U.
On mine, I removed the swing arm, cut and bent it so the wheel would clear and then re-welded it at the new angles.
I also chopped the rear fender to clear the tire movement since it's a soft-tail upward travel would cause the tire to scrape.
I don't see a problem with raking a moped. They are pretty much crap for low speed maneuverability as is and high speed wobble isn't an issue (unless you know how to get a moped to do 60mph). 35 deg. sounds good to me.
Problems. As a chopper, my puch is impossible to pedal any good distance.