That is far more common then you think.. IF your coach is indeed 50 amps, you can re-balance, putting at least one of those dual breakers on the left, I would/did in my coach.
Also, you may wish to make sure that is how it works (This takes an ohm meter and NOT being plugged in) They may have changed the bus arrangement in the box Mine is a 1 2 1 2 1 2 type not a 1 1 1 2 2 2 type But then mine is a progressive Dynamics box, not made in China.
Now, on the issue of Progressive Dynamics, You might want to look at the 4600 line, May (or may not) fit in the space provided by gutting the WFCO better.
Since I can not possibly upgrade the converter Damon gave me.. I do not know (Progressive Dynamics 9180 with optional charge wizard, basically the same as what you are considering, in fact other than size it is identical).
Once you drop in that PDI wizard job,, You too will be unable to upgrade.