Spare tire holder ideas

I might be tempted to rig something up on the tongue if there's room there. Since that's not an unheard of place for spare tires for trailers, there's a good chance some off-the-shelf holders would fit or could be made to fit fairly easily. There might not be sufficient room, though, while still giving proper access to the LP bottles and the jack.

THIS is the one I use. I mounted it to the rear TT bumper. It swings down & out of the way, so I can access my rear cargo door. I suspect your TT has a pretty strong rear bumper & may not need any additional support, but it's worth checking.

I would look into something like this. Your trailer sites pretty close to the ground in the photos of one on the net.
You would need to check your rear trailer bumper to make sure it stout enough to handle the weight. Option would be to add a structural member between the bumper and rig between the frame rails.
Tire carrier