Yeah, Tirerack was my first stop when looking for tpms. Their systems only work with 4 tires and RF range could be an issue. I need 6 for the trailer and wanted expandability to add the truck tires in the future.
I googled my way to the RV forums for most of my info.
To speed up others searches here is some the names I came up with:
Doran, TST, Tire Traker (Hawkshead in Canada, Jet down under), Pressure Plus, Pressure Pro, Orange, Tyredog, Hopkins (universally disliked on the RV forums/Amazon), AirAware, TireStat...
None of the systems were exactly what I'd want. I'll be heading to Florida (PRI) in December to test the TireTraker I ordered.