More than answered my question, thanks Gary!
I was also curious as to the amount of tension you are generating and in a way, surprised to find that even with the skins torqued down you can still easily adjust the stop...
There is still a part of me that feels as though the plastic dip or some rubber stoppers would help my concern for any rubbing. I'd probably be pretty anal about making sure they weren't touching the shell at any point, especially before a performance.
As for spurs? The first thing that popped into my head was something similar to your snare and butt plate assemblies, running from one tension rod to the next. Maybe just one on the bottom with legs extending out?
^^^ drawing of the year, my friends.