[folivier]

These are the split basement units and not rooftop right? If basement then any AC guy should be able to recharge them, if they want to. That's what I found is when you mention it's a motorhome most guys automatically say NO. Maybe find a small local AC shop and drive into their parking lot (if you can fit of course) and maybe they'll do it there.
On my 1993 there were service ports already so that made it easy.