Is the pic taken straight down from above? If that board in the pic is the bottom of the coach, can you get to the bottom side? An effective but inelegant solution is to replace the valves with elbows and add caps outside and below. Or even valves down there.
Is the System Drain the low points for both Hot and Cold water? Those are usually separate valves, so replacing the combo/cold/hot drain with separate ones would make them easier to get and in my view easier to use. I don't always appreciate the parts Jayco used on our coach but I do like the 1/4-turn brass valves they installed for water control and low point drains. They use crimp fasteners, though, so you'd need to buy/rent/borrow a crimp ring tool. I'll see if I can find pix of the valves.
