Plenty of us have.
We pulled out our "I-Deal Rest" RV King mattress 4 years ago. One of the controller's wires got pinched once and one whole side of the mattress was unable to work. I fixed it easily (
the cable is a simple Ethernet cable) but decided I didn't want a bed that needed electricity to work.
First, your bed is a custom sized RV King. 2" narrower than a standard King and 2" shorter, too.
It's easy to have a custom mattress made to fit the space - check out
www.brooklynbedding.com or
https://www.mattressinsider.com/rv-mattress.html - but we went with a stock California King foam mattress from an online seller (
www.leesa.com).
The Cali King is the right width, but still 2" too long. So, I removed the kind of ugly headboard held on with 4 small screws and that provided plenty of room for the Cali King.
Everyone worries about the bed tilt and if you ask someone at an online mattress store they say, "
Gee, I don't know if our mattress will work." But ours works great and that's after 4-years. The I-Deal Rest was 10" thick, so I did make sure to buy a mattress that same thickness.
My old I-Deal Rest is in the attic gathering dust. And, we don't miss it at all.
Here's our Leesa California King installed without the headboard: