There are some threads here as well as other jeep forums that will give you a better idea of the task. Do a search. There are some that are pretty detailed. It is a time consuming job and one of those you say ..."will this s*** ever end"? I would take and have the evap "sniffed" before I went that way. There are alot of other points you can dump gas.
I have been looking everywhere for the leak and it is nowhere. The only clue pointing to evaporator I have is the scent in the air inside the jeep smells of r134-a.
you will notice it even if the engine is off and it sits, the interior air develops a goodly odor of pag and refrigerant. It takes about 3 weeks before it is all drained out of the system.
If its that strong in the cab you are prob on the right track. See how much a a/c shop would charge you just to snif the air duct, leave the system off before you go. If You know anyone that works on central heat and cool systems the sniffer they have will work as well. 134 is still a halide and will be detectable.
I use one at least once a month on heat pump evaporator coils and yes they will false read if gotten wet. But more times than not its dead on. If youhave that bad of aleak in the evap coil and sniff it at the duct after the system has been off, accumulated gas will set it off quick with just a short burst from the fan. Just want you to be sure. This job is kinda a pita.