I looked into using a reefer unit/cooling system last year and decided against going ahead with the project. Here are my reasons:
1. The noise of the units are restrictive. They would be unusable in an area in which others are trying to sleep.
2. Vibration of the units within the rv.
3. The size and layout of the units pose many, many challenges to fitting on an rv, even in a basement layout situation.
4. If you decide to plug in for a few days, say at the house, a park or whatever, the engine on the reefer unit needs to be run to cool the bus. Or you will require a roof unit also, which increases the final price and makes dual systems redundant.
5. Finding a reasonably priced reefer unit that still has life in it is a challenge.
In the end, the idea of a 13,500 btu roof unit with a kimpor (honda eu knockoff) seems a simpler and cheaper system.