Re-reading this string of comments on the parking brake issue, it reminded me of our experience in Alaska last summer (2006). We didn't have our Alpine at the time, but a couple with a Country Coach stopped at the same campground as us and couldn't get their parking brake to release. They confirmed low air pressure due a problem with the pump. After messing around trying to get air pressure from the pump and failing, another Big Rig owner came by and hooked up his air hose from his auxillary fitting to the auxillary fitting on the Country Coach, and used his coach to pump up the air in the Country Coach enough to release the parking brake. So I don't think it helped the Country Coach owner keep his suspension inflated but it got his parking brake released and allowed him to drive on to Anchorage to get the coach fixed.
Don't know if this would have worked when you had your original problem at Arches National Park (we stayed there last month and liked it as well), but it's a thought on how to release the parking brake when you can't get enough air to it, unless the leak is too large.
Former Owner, 2006 36MDDS
2010 Arctic Fox 22GK Travel Trailer
2007 Toyota Tundra