"be discrete if that winds up being our choice." You've got more 'guts' than I do! Discrete or not, legal or not, 5er or MH, it's simply not safe, ever. Which ever direction you go, keep seat-belted in, in a real passenger seat.
Sounds like your a candidate for a small Class-C towing a flat trailer for your secondary vehicles.
FYI, you REALLY, REALLY need to watch the entire movie "The long long trailer" if you've never seen it before. It should be required viewing for any RV 101 class! It is full of do's and don'ts that are just as much relevant today as they were 50 years ago! The second movie you should watch is RV-the movie with Robin Williams. This one should be required for the RV 102 course!