At one time I had looked into replacing the receiver (Jensen) and found it was very difficult to find something that would just fit into the hole with minor modifications. I did not want to reconfigure the entire cabinetry so forgot about it. Decided instead to upgrade the speakers. The Jensen units tend to publish their peak wattage per channel vs rms so they can be deceiving...and their outputs are pretty low which makes a more efficient speaker beneficial.
I upgraded the living area speakers to Kenwoods and it made a big difference. It is not an audiophiles dream but much better than original. Didn't worry about the others because none of them have ever been used. Wasn't worried about a sub or monstrous bass because we stay where there are other campers generally and an RV wall just won't slow down the noise and vibration.
I won't get into the quality of Jensen vs home units or even auto units. Most of the higher ends of both types have been really massaged for higher/cleaner outputs - but then again, the number of autos and homes far eclipse the number of RVs. That combined with RVs being constructed with the cheapest components to get by....you get the picture.
I had thought (and it might work for you) about just buying a smaller unit that didn't fit the factory cutout, take a piece of veneer or wood that closely matched the existing cabinetry grain, stain and mount inside the existing hole. Doing that should open the choices to some pretty high end auto head units with better specs. Or, just buy a home receiver and bypass the existing unit. We leave our blu ray player just sitting on the counter under the tv on non skid material and it has never moved; I suppose a receiver would do the same....if you have a counter under your tv.
