Son-in-law and I built one with square tube into the receiver and a cross-piece channel for wheels to rest in. A vertical brace with angle cross-piece at nearly the top of the forks. This was all welded and is one piece. I use a locking pin when installing it on the car.
Foam pipe insulation is installed on steel pieces where the bicycle is nearby. Also, a piece of foam insulation is put in across tire/rim in the channel to avoid tire shifting sideways in channel.
I use woven nylon bicycle toe straps to hold my bikes on my rear rack. One such strap on fork at top cross-piece. One strap on each wheel in channel. One on backbone to the upper cross-piece. One strap on a angled cross-brace to the front wheel to keep it from turning.
Does this bicycle make my car look small?
A few years ago, though, I did buy a new high wheel carrier - a 2014 Chrysler Town & Country. I put it inside. If too much other stuff is inside (e.g. wife's modern tricycle), the high wheel goes on the rear rack. I have loaded two safeties, a Fairy trike, AND the 56" Expert inside along with exhibit material for events.