temp probe location?

For a self-made rack with 5 shelves and using one t-stat for the 5 flexwatt strips in parallel, would you place the probe on the top shelf so that would be the warmest any of them will get or the middle so to be the mid-point of your temp range?
I also was wondering if there is a way to use 2 probes on one thermostat, or do I need to just get more t-stats?
The whole rack + heat will cost me less than one Helix and I'm probably going to make two. So I'm hoping to be able to save money but still do it right.
I've looked at ppl's setups on here, but not quite finding the answers. Any tips appreciated!

I'd put it on the top shelf, because heat is what could potentially kill your animals, so you have to control the uppermost shelf, or at least know what the temp is.

You know what would be cool- if you're building your own. Have two separate heat zones in each rack (with the racks side by side) upper and lower, and have the lowers on one stat and the uppers on one stat.

Herpstat makes a model with two probes, that allows you to set two different temps. The Night Drop has two probes, but it only controls one set-up.

(But most stats allow you to plug three items into them, as long as you don't exceed the wattage rating).

okies, along those lines, hmm. They are going to be side by side... You have me puzzling things.