FWIW, just a quick update to this thread. Since the plumbing upgrade I've made three trips between Alaska and California and several interim camping trips with the family. I have another Alaska trip coming up in a couple weeks.
The only thing I've changed since the plumbing upgrade is the faucet, which is detailed in this thread.
Inexpensive 4" on-center pull-out faucet
The new plumbing system has worked great whether hooked up or boondocking
Unfortunately the Apollo PEX fittings are no longer sold by Lowes (none that I've checked with in person) but Apollo seems to still be in business. I plan to get some spares to keep on-hand so I don't have to rely on a local retailer if something fails down the road. So far though, knock on wood.