Ray-- You might want to check the position of the "cooling switch or panel"! It is the little white (that's what color mine is anyway)deal slid over the far right fin on the cooling fins in the back of the refrig with a wire running from it! If that "switch" , or whatever you call it, is anywhere besides the upper part of the right fin it will not cool down as well and will take much longer to cool. Slide that "switch" up to the top of the fin and it will cool a lot faster. The ice ideal is also a good idea. I always put a frozen gallon jug of water in the frig when I first plug it in and it cools much faster that way also. I also do this when I'm on the road from home to the camp site. I don't run my frig on gas unless I absolutely have to. If I get it cooled down before leaving, the ice jug keeps it cool enough for the first day anyway. Of course we don't have the DRY HEAT you do up here in NE either!
I don't know what model of Monte you have but check the refig recall by Dometic also. Get the model and serial# of your refrig and check on the website for a recall on your model or not! There are several threads on this recall. It doesn't have anything to do with the cooling like you're asking about but does concern the safety of the refrig and possible overheating and fire caused by excessive heat when the frig is run on gas!