If I can find in the state or VA / SC will work. Adjustable would be find but custom would work if the price is right. I would assume most dealers could set up the trailer with out the boat?
GW has the info for basic set-up. They gave it to me for a trailer I just bought. If not set up for your hull, some final adjustments will be needed to make it fit 100% correctly even with the info from Grady.