Tub setup questions

So I am going to be possibly rescueing two 5 foot BP and as they are currently in glass tanks I was thinking of making a small rack setup to put them in as I plan on getting more and as I live in an apt it seems best way to go. How is flexwatt used and such? I have no experience with tubs so I am kind fo a noob in this as all ym snakes I have owned lived in glass tanks. Is it expensive to geta tub setup and such? I am guerssing no more then a glass setup. from what I saw on a post here the flexwatt goes on the back wall of the rack behind the tubs? if so do most flexwatt bundles comes with instructions on setup and such and where with flex do you put your temp probes and what is best way to regulate the temp on the flexwatt. Also does flexwatt cause power bills to go up much? I am nto worries as I can afford it but just need to know.

Flexwatt can be taped under the warm side with metal tape, but you will need a rheostat or tstat., no your power bill will not go skyrocketing

Flexwatt is a good DIY under tank heater, I love messing with it. Since you only have two snakes and are only going to need two tubs, youll need 2feet of 11" Flexwatt and a repti-temp500r to manage the temps. An acu-rite thermometer or two are definitely in order as well.