There are a couple pictures of the retrosound unit installed in a 96 XJ in one of the reviews.
https://www.crutchfield.com/p_068GRANM1B/RetroSound-Grand-Prix-M1B.html?tp=49934
What year is the MJ? Put that info in your signature so we know what we’re talking about.
Both my 88 and 90 AC MJs have the sensor in the radiator, not the hose.
It was very cramped with the WilderNest down. My wife slept on the truck bed (on the mattress) with one dog and I slept on the drawer (foam pad) with the other dog. There isn’t much headroom on top of the drawer but it is what it is. The only change I would make is keeping stuff a little more organized making the move down quicker.
Got back from camping, one night we had constant 45mph winds, had to take down the WilderNest and sleep in the closed up camper. But here is the shower at work, the dogs loved it.