MOUNTING LOCATION FOR TEMP SENSOR ?

With a cord, that somewhat limits your choices. Probably to get the best readings, try to find a way to drop it through the floor, and mount up under your rig. It really needs to be out of direct sun and wind, so under the rig would probably do both. I would try to find a sheltered place and maybe shield it with a plastic cover.

What about under the toilot vent cap? Just thinkin out loud here

I glued a couple of magnets to the back of our sensor. I can attach it in lots of places and move it around out of the wind and sun as needed. Works great.

I have wireless unit and the remote is mounted to the pi box of our 5er. :)

I put my sensor in a ziplock baggie and placed it inside the propane tank enclosure. I used a twist-tie until I'm sure where I want to mount it.

WoodGlue

Try the propane compartment. You might need to try several spots to find one that is not effected by sun exposure or exhaust pipes.