I just returned from a trip to Home Depot. I was told by the guy in their Plumbing section that the Sharkbite connectors won't work with the planst water lines used in RVs. He claimed to work on RVs and mobile homes and said the plastic lines from Indiana RV suppliers were "odd" sizes and won't be compatible with Sharkbite connectors. To be safe, I'll probably go with the plastic connectors mentioned above.
I don't know that I'd take his word for it. I've used Sharkbite fittings on several occasions now and if you have standard 1/2" pex line, they work just fine.
I routinely use Sharkbite, Watts, or Sea-Tech fittings from Lowes, Home Depot, or our local Ace hardware store on RV plumbing. And as mentioned, I always install a shut off in the toilet supply line. Toilet flush valves tend to be a relatively high failure item, and a shut off means you won't need to shut down the whole water system if it fails.
It's been a while, but I just want to post an update. I eventually installed the new toilet. I just used a standard, 1/2" flexible water supply line for toilets. It just loops around a bit to make the connection. It's not pretty but it works and I didn't have to cut the water line.
As a warning, I almost stripped the plastic connection on the toilet with the metal connection on the supply line. I even tried to be careful while making the connection. It went on without any resistance, but it wasn't quite straight and it chewed up the threads a bit. I was finally able to get it on with no leaks so I'm now set.
When I hooked up the water for the first time, I was disappointed to learn that the water line to the shower was split. The previous owner must have left water in the lines during the winter. It had an 8 inch split down the length of the pipe. I didn't find out until I noticed a water fall coming out the back of the camper. I had no choice but to cut out that section of pipe. I replaced it with the Sharkbite connections and plastic PEX pipe. I noticed that the circumference of the original water line was just a little smaller than the PEX pipe, but it worked perfectly. The Sharkbite connections made it an easy fix. At some point I may go back and do the same thing with the supply line to the toilet.
Thank you to everyone for your advice. I appreciate it and I'm no longer afraid of replacing any other water lines that may cause a problem in the future...