Ok, been there done that! We have the identical Concord as you do--same year model, everything. We had our dealer upgrade our AC to 15,000 after about 6 months. It may have helped a little, but not near enough. We are now considering adding another AC. Yes, I know we only have 30 amps, but we will have to plug in to the pedestal to the 20 amp plug separately. Living in Texas we don't use ours much in the summer. It is just too hot! We park in the shade and cover the skylights in reflectix and also the cab area. We also use fans to move the air around.
If I had to do it all over again, I would have kept my 13,500 and just added and additional AC instead of replacing the one I already had. I hope this helps. Other than our AC issue and heat in Texas, we love our coach.
Jim