I mounted my spare between the rear axle and the fresh water tank. I put a cross on top of frame rail , then I mounted to the cross piece a 12v cable winch and two long 3/4" bolts. Then I made a plate that fit across rim ( rim center, mounting holes ...
I use a Tempstick to monitor house temp on my i-phone 24-7 and for water in basement a water bug it is hooked up on land line it will call your phone 3 to 5 times depending on setting and up to five phone #s $150 for TS & $55 for WB