[Alpine]

Well now.... Welcome to the "Information Station!" I did a brief look at the specs of your travel trailer and it is very nice indeed. There will be other members along with more technical info and fixes. What I did notice however is that Keystone put only 1 AC unit on a 37 foot travel trailer... that is asking a lot from one AC unit. However there are a couple of simple inexpensive things to do to help your "right now" situation.

If you have the regular floor vents coming from the furnace, they can be covered with "magnetic floor vent covers" purchased from any big box store, Walmart, Home Depot, Lowes etc. This will keep your cold air from filling up your duct work coming from the furnace. You can also make a cardboard cover for the cold air return vent(s) that go directly to the furnace.