[bestgenman]

You had asked about the output of the genset and the associated cabling.  A 20KW set delivers ~83A and thusly is protected by an 80A overcurrent device. (I know you know all of this but for the benefit of our GURUS)  The shore power feeder is 50A and the XFER sw is rated accordingly (usually 60, 90 or even 100A contactors), the feeder from the XFER is landed on the MAIN LUGs of a main lug only panel (no main breaker).  The 50A breaker in the panel feeds the buddy plug.  Newell has typically installed #6-4 SO cable for power feeders including the feeder from the genset even though the Generator breaker is 80A.  So, when you are on generator the overcurrent protection is 80A (from your generator which exceeds the cable's capacity).  The reasoning here is, if you can use your coach's system under normal operating conditions from a 50A shore power, you are not likely to exceed a 50A pull from the generator.   I don't think I have ever pulled more than 11KW with the AH on and two ACs plus Edith cooking.

 It would certainly be possible to re-pull that cable with 4-4 or even 2-4 (but that might be a bit of as squeeze) to your inverter bay.  And, here again is it worth it?

My disclaimer:  All Newells are different and later models, than my 2000,  may have different sized wiring.

Really enjoyable post and do come to Bella Terra.