Anyone remount spare under the trailer?

I did the same thing for a bike rack. I just took off my bumper mount and fastened it to the frame underneath. Worked real good except for going in out of some campgrounds and service stations with large dips in the entry. I had to take mine off because it dragged and was rubbing the tire. Perhaps it would have worked if I mounted it closer to the axles. However it would have been a pain to get the tire off if it was needed.

So I gave up on the bikes and put the tire back in it original position. Sorry not much help but maybe you can gain from my experience.