Wil - First - congratulations on this fine purchase - you will not ever be disappointed in the unit
(This is for an xtracab) I located my Engel behind the pass seat ( so I could still recline if I was solo) I did not mine loosing the mini storage space under the floor - and the slide-lok was less $$ - I used the Slide-lok and mounted it on a piece of 3/4 ply and screwed it down to the floor where the mini back seats fold down to it over hangs onto the fold out cup holders - I can remove it at anytime and bring the back area to stock with four screws.
Foot note: if you store most of your food in Zip lock bags your fridge will stay cleaner longer - making the removal for cleaning less. This will also help you to layer food depending on when you need it - I was able to keep food frozen at the bottom and kept the fridge at 32 degrees keeping the food on top at appox 45 degrees -
Last tip - get a temp gauge so you can monitor it - I have the simple Engel one you drop the one end in - I mounted it near the back window so I can see it in the mirror.
Other notes - when wheeling hard or washboard roads the fridge does have a small amount of movement due to heavy vibrations - this appears due to how the slide lock - locks the fridge in place and how tall the fridge is ( leverage)
I am ordering another Engel for the 80 series with the Engel slide and will be able to see if that mounting system is more solid