Yes, I did this. Found Sharkbite brand quarter-turn valves at Lowes (there are other brands out there, too). Was simple. Cut the pex and pushed on the shut-off valves. Simple as that. So much easier when winterizing.
just about any lowes, homedepot will have these valves, they are 1/4 turn valves that we use in our homes. you can take the plug with you, match the tread size/pitch up, bingo, done !. i did this on my fresh water tank, as said, will be a lot easier come time to winterizing.