As most know, for every 90 or fitting there is a bit of a friction pressure loss. Really not enough to affect this system, but there is some. Depending on your set up, you might be able to completely eliminate the piping under the sink, and just put a union in somewhere opposed to the U shaped insert. In one fifth wheel we had, it was way up in the wall between the shower and TV. In this case, we traced everything back down to the basement, and probably eliminated 6-8 feet of pex line and 3 fittings.
While at different factories, I've questioned this valve, and stated what I had done. All have said similar statements. Well, we're required to do it this way, but there's really no reason why you can't do as you've done. I understand why they do it, but the valves are so cheap, and usually leak just as the OP's has. In most cases, this is in a wall, or under the sink. To the guy who doesn't know about these valves, he never checks them, and LOTS of damage can be done before it's caught. I got lucky on the one in the wall, and happened to see some dripping coming down into the basement. From that point on, I've always eliminated that potential and just removed them.
John and Rebecca Dickson
Emma-7 / Little John-5 / Iva-1
Full Timing Again, Rev B
2013 Ford F-350 Lariat CC LB PSD
2015 SOB TT - With OC's Awning Poles (#8)
At least in Heaven, RVs will be perfect, and I won't have to keep fixing them.