Remember 1) You'll never get your money out of a homebuilt 2) There are substantial libilty issues if you (or your heirs) ever want to sell a homebuilt and 3) Your life insurance probably won't cover you if you auger in in a homebuilt.
Once you get past that, build a T-18. Same performance as an RV for half the money. Better yet, buy one that has been built already and then get an extensive pre-buy by someone who knows the type intimately.
Not that intimately, of course.