I definatly want to test the electrical. Here is how.
while on battery power, Turn on a few interior lights, then turn on the stereo. With both on, lower the electric bed. All should work okay. Next, keep an eye on the face of the salesman or whoever is doing the PDI with you and trry to raise the electric bed. It probably will not move. Turn off the lights and stereo and it will probably still not raise up. Just to prove there is a 12 v problem, turn on the genny and watch the bed go up w/ lights and stereo on. Have them fix this before you accept the rig otherwise you will spend the time and $400 I did on replacing the Paralax converter and upgrading the 12v cable from the battery to the converter. See that here: My 12v Upgrade
Ragen makes a fine rig, their 12v guys just don't know what the heck they are doing.