There are many things that affect the effectiveness of the A/C. since you said you are a HEVAC technician you likely have the tools needed to measure inside and out side temp's both at the air intake and outlelt (Both sides of the evaporator and condcenser) and you should know the book and be able to measure humidity as welel.. You SHOULD know more about this than I do since it's your job.
Thaqt said, there are things you might not know for this takes not a technician but an engineer (Guy who designs the system)
Things like what color is your RV.. When my wife was alive she choose the color scheme for my RV, it's dark, sucks in sun's heat like a vacuum cleaner sucks stuff... So on my 37' RV even with two 15K's it warms up a bit (Like 80 to 90 interior) in the summer. Had we gotten a lighter color we'd be better off.
and that is just one thing my Pre-Engineering study taught me. There is more.
Closing curtains, Use of Reflect-x (Silver stuff you put in windows) and so on will improve yorr life.
