I was going to go with the Kaymar, just bumper, for starters. I agree with you, I don't much care for the tire on the back, but it is useless underneath.
If I could get an auxilary tank, I would then opt for the Kaymar arms and move the spare to the back.
I think this is one that you may want to hold off on, and see what comes out, and what challenges and experiences others ...cough(DTT)cough... have. It also depends upon the purpose of the rig. Right now mine is a daily driver and wheeler, for that reason I will keep the spare underneath. I could see me getting something else in a few years and it turns into a road tripper / wheeler. If that happens, I will be willing to move the spare to the back.