I'm in Quartzsite and while I haven't been to Parker I have been closely monitoring the local chatter page on facebook. Over the last 24 hours and even within the last 45 minutes a number of people have posted about shopping in Parker, that the stores were fairly well stocked and gas is cheap at $1.90. In regards to the Tribal order, not one person reported anything unusual as far as tribal enforcement, it seems to be a non-issue for people going to Parker and shopping there.
I just did a resupply of food items yesterday and stayed in Quartzsite because I wanted to avoid the busy scene of Parker. The stores in Q were not crowded, people were friendly and respectful of space, and while some shelves were depleted, I was able to get everything on my list. At the Coyote I even saw people leaving Family Dollar with packages of toilet paper!