Engel 45 Fits in Mine
I have an Engel 45 in mine, behind the driver's seat. I can slide the seat all the way back, and recline about two notches before my seat touches the fridge.
I used four turnbuckles to hold it in place: two connected to the stock seatbelt attachment braces, and two more to an aluminum L-channel that I bolted to the front of the seating area (where bajataco attached his 2x4 for his custom support – I want that in mine too).
The fridge lid will not open all the way – it will hit the roof at about 75% open – but still opens far enough to take out the basket without removing the lid completely (which is super easy and I do all the time).