You have a golden opportunity to avoid the Jensen and iRV brands.
The blank out panel may have already been there from the factory. All Jayco trailers come fully wired with speakers even if you don't get the package with the entertainment system. Knowing that in advance, we didn't get the entertainment system on our '03 Kiwi. I simply popped out the blank and installed my own car head unit. Our current Jayco was purchased off the lot and came with the Jensen.
Look at Crutchfield's
web site for options. Better yet call them and explain what you want to do. It may be they can recommend something far better than a junky Jensen for the same or even less money, and set you up with a mounting kit for free or just a few extra dollars. Crutchfield also provide free lifetime tech support.