I, also, have been fortunate to have visited Sonny's place a couple of times.
If your AC loses a Freon charge again it might indicate a leak - my experience is that they (leaks) are hard to find, more difficult to fix, and one leak will usually be followed by another one.
I found that it is not that hard to replace or install AC's - have done three so far.
I have always used Dometic heat pumps - the one most difficult thing I have found is to get the proper drain pan for the thing.
My experience is that the unit provides capable heating well down to the mid-30's.
As an aside, I have been living in the '78 Sovereign
for the last month while on a contract job in the Eagle Ford in South Texas. No shade anywhere and unable to put the awnings out. A single Dometic 13.5K will only cool to 10 to 15 degrees below ambient with the trailer in full sun.
This means that when I get back to the trailer at about 5:30 PM, ambient temp is 98 F, inside the trailer it is 86 F. The installation of the second AC in the rear was a huge benefit. With the front AC on all of the time, when I return to the trailer in the evening, I turn the rear AC on the inside temp drops from 86 to the mid 70's in 15 to 20 minutes.
The park owner sent an electrician around the other day to do some maintenance on the electric boxes and the electrician left my breakers turned off. Outside temp was 96 F, full sun, inside temp was 106 F.
Only vent left open was the bathroom overhead vent with no fan.
Did you know that Ghirardelli chocolates will melt at 106 degrees?
What a mess! The bag of Ghirardelli's was in an overhead cabinet over the sink, and melted chocolate and delicious creamy interior were dripping everywhere.