Thermostats you have linked to are to regulate the temperatures produced from the heat source, usually a heatmat, Yes you can use aspen bedding, and the temps should be round about 27 to 30 degrees.
i use the first one, just plug the mat into the socket on the device, put the probe between the mat and the faun and then plug the stat into the wall and bobs your uncle what are you keeping him in? if its a plastic faun then make sure you have the mat outside and underneath it, if its a wooden viv (at 6months its probably too small for a full viv though) then it goes inside aspen is fine to use, just dont pile it on too thick (1-1.5cm is fine) in the warm end but you can make it an inch deep in the cool end
2.0 Normal Royal Pythons - Q and Little One 1.0 Chihauhaun Mountain Kingsnake - Simba