Make your RV port extra, extra oversize. I made mine 14' tall because my last MH was 12'6". Also give yourself plenty of room on the sides to open doors, deploy slides, and have at least a foot left over on each side. You'll also want at least two feet on each end to keep most of the rain off. So my thing would be to overbuild, overbuild, overbuild. Besides that, someday you'll decide you want more than a 22' trailer. My original MH was 26' and now I'm up to 32'. RV port is 32'. Therefore I end up with wet ends on the MH.
2015 Greyhawk 29MV
Honda CRV toad with Blue Ox baseplate
Ready Brute Elite towbar with braking system
TST 507 Flowthru TPMS