These and other brands have been getting smaller and the amp loads are almost small enough to make these type compressors a viable replacement for belt driven compressors. This is just an example of the many 12v DC compressors out there. I have been looking at these for several years. The sizes and pricing have been getting better all the time. There are some with a 30-40 amp load capable of the 2500-3500 BTU range. Some of the horizontal type are just a little longer than a quart oil can. About the size of a "Big Gulp" cup. Many that are doing engine swaps are finding restraints with room in the engine compartment. With that many have already increased their alternator capacity. These could be mounted in the front compartment without hoses and shaft seals to leak. Could work with the stock condensor and evaporator. I'm asking if anyone else has been looking in to this with more detail.
Personally, I'd prefer a solid state solution, but getting it cold enough can be difficult. Great thing about a good solid state solution though, is it could double as the heater and a/c, which means a lot less fluid line routing, and a lot more surface area for the air to contact.