I too prefer keeping garters in other set ups besides a rack, for the same reasons of mental stimulation (traffic outside the tank) and for their love of basking.
But, with many babies the rack is quite handy (and I keep a few other species on it as well)
I have found that the steel and wood shelving systems from places like home depot are good for holding multiple glass tanks, and you can drill ceramic sockets right into the shelf, these are what i keep my adult garters in
