A tip from a coworker pointed me towards a very large beach very nearby. A short drive in the early evening, minimal searching for the TH, and a ride past a gate down a dirt road brought me out onto the sand.
Massive. 200 to 800+ yards deep, dead flat, and going on for miles. Huge lake to the south, valley to the north, small mountains to the west, big mountains to the east. Firm sand, a bit of gravel, and the occasional half buried snag in the middle.
Especially relevant now that all my river gravel playgrounds are underwater. I will be back.