I have yet to see a vehicle park perpendicularly on the trail. the pic below seems to be the preferred method, and the method that would work out for all concerned. Notice that a trail sized swath easily cuts thru the Conrad's area, and yes, those are Conrad guests getting on their bikes. Warms my heart.
At the moment, yes.
edit - actually, at the moment there are 9 vehicles parked 3 up parallel on the trail blocking the entire thing. Most are news vehicles and there is security, so something is going on. Not a usual situation.
Regardless, I've seen tons of valet activity on the trail, not one pulled in perpendicularly. If I was a valet, parallel would be exactly how I'd do it. For those guys it's all about speed and ease of access, rules be damned.