new rescued 6foot red tail boa??? heres a picture and question..

[redtailboas213]

I just got this red tail boa a couple days ago.. I put it in a 4 feet long tank for now.. (55) gallons.. I put a heat pad under tank but the glass got really hot so I went to get a zilla thermostat.. I put the probe directly on glass since he/she burrows through newspaper and didnt want snake to get burnt.. I just went out and got some aspen also.. Now my question is what can I put on bottom of aspen so he doesnt lay on bare glass and get burnt??? (he/she likes to burrow) Should I tape newspaper or old shirts on bare glass and lay a little aspen on top of that? heres a pic of him/her.