Hi Gary
I'll probably be of little help to you because after researching things pretty thoroughly I went with the Viair. Their RV models are a simple build, very high quality unit with a very small footprint (12.5"X6"X7.5"). I actually like the 12-volt battery hookup since it just takes a second to set up. I just pull the compressor out of the rear storage drawer, open the house battery door and slide the batteries out, clip on the clamps and with the 30-foot coiled hose reach every tire on my rig. The negative is cost--the 400P and 450P kits run from about $200 to $300 depending on the specific kit, but these are nice units--automatic compressors that operate like your water pump--only run when you're actually injecting air and immediately shut off against the pressure in the line if you stop to check pressure or move to another tire. Be careful of the "ratings". I bought the 450P, since it is a 100% duty cycle compressor--can run an hour straight if you should need to without cool-down (many small units are 30% duty cycle compressors). It's a 150 PSI (max) compressor that can actually inflate a tire to 130 PSI if needed (most similar compact units can't). The 450P-RV kit also has a second 30-foot coiled hose that provides 60-foot reach if you should need it, canvas storage case, and a hand gun with extremely accurate gauge that the screw-on and direct-connect chuck attachments clip to. All-in-all a really nice unit that should outlive the RV.
After all that, I hear your original comment: "....not to break the bank on something I'll hopefully not use frequently." That is a reasonable consideration as well!!
All the best with your search, Mike
