When you allowed for space on the 80l was it the normal (chest type) and did you allow for the power cord to go in. If you use the dimensions out of the brochure they don't allow for the space needed by the plugs which come out the front long side, not the back like the 39's, which I rapidly found out when I got a 75 combo.
We ended up with the combo cause it was too hard to keep meet iced, and lettuce etc not iced in the one un-split fridge/freezer, and we didn't really have enough for 2 seperate ones without an elaborate storage system in the back of the patrol.
There are good arguments for 2 smaller, and arguments about the energy needed to make ice for eskies etc, sooo....
Good luck
Paul