If you go that route, I'd suggest securing the rear of the bike otherwise it'll just flop around. What you might want to do is buy something like this and some pipe brackets to anchor it down to a 2x4 running perpendicular to the one for the fork mount. Just make a "T" out of two 2x4s be securing them at the intersection with a metal joining plate.



BTW, here's how I secure my bike inside my SUV when the hitch rack fills up.