We live in Southeast Pa, so it gets pretty cold here too. We drain the fuel; drain the water..refill with antifreeze…drain again; bleed the brakes with fresh fluid; Tri Flow the cylinder and bottom end bearings; remove the batteries from the gauge and kart (Tag); rebuild the carb; wipe everything with WD40, Triflow, and/or PB Blaster (? pipes, axles, etc). Then in the trailer they go without heat. New tires, electric starters, stop watches, distilled water, kart batteries, weather station, etc go in the heated basement.
We’ve been doing it that way since about 1990 with no ill effects to anything.