Did you try going to the carwash and using the wand?
Probably too expensive unless you had a helper to set up and flip the LPs.
Besides you'd get the labels wet.
But if you do go, make sure you use the faoming brush though, The mechanical action really does a better job of cleaning, well at least on my Explorer
I'd avoid the Wax cycle...

Got some Streisand too, if you can stand it.