Accumulator Tank, you have the parts
My pump is in a bay under the head of the bed and cycled constantly even with just a trickle of water. To help silence the pump I suspended the pump with straps from an overhead frame in the bay. The pump is suspended in place by the two braided water lines and straps. It's not solidly attached at all. That helped a lot with the noise. The constant cycling can't be good for the pump or switch. I needed a bigger accumulator tank.
The water heater has a small air chamber that functions as an accumulator but the air is quickly absorbed by the water and has to be recharged. I have removed the drain plug and put in a nipple plug, hose, screw on end cap and shrader valve. This lets me add air easily and drain the tank easier than getting wrenches to remove the plug.
The Sureflow tank has an internal bladder which solves the absorption problem and has 42cu. in. capacity.
An accumulator tank can be any size or shape, just needs to be attached to the water system and hold pressure.
I add water by gravity or city water connection. If I empty my white water hose, connect it to the city water connection, defeat the backflow valve and cap the end, my 50ft. 5/8" hose functions as a 184 cu. in. accumulator tank rolled up in the storage bay. Now a good bit of water will flow before the pump cycles on and to connect to city water, just pull the hose out and take the cap off.
To defeat the valve, it could be removed, but I just inserted a screened washer in the line to hold the valve open. A screened washer like is used in clothes washer hoses. The crowned screen holds the valve open. I gave this a try this afternoon and all worked fine. We'll give it a real test next week when we go to Lake of the Ozarks.
2015 Itasca Sunstar 36Y w/2012 CRV toad