[Derby6]

You can do it anywhere. Parking lot if needed.
Lots of way and you can search on here for procedures, air, pink antifreeze, or both.

I just use pink stuff.
Get rig ready to go and do final gray/Black dumps, rinsing as best you can.
Close dump valves.
Disconnect from water and drain fresh water holding tank.
Release pressure from lines, especially hot water heater. (I catch water in a pan and dump outside.)
Drain hot water heater.
Bypass Hot water heater.(This procedure varies based on year and model)
Drain lines at lowest point if possible.
Find water pump lever that controls from fresh water holding tank to winterize. (This procedure varies based on year and model)
Hook hose from 2nd water pump hose (likely in place) or marked area where it states winterize in to pink jug.
Close all open lines you opened to drain/release pressure.
Turn on water pump.
Go to lowest or furthest point and open cold. (If going in to a tank, I catch water in a pan and dump outside.) Once it turns pink let run a few seconds into drain. Switch to Hot and do same thing. NOTE: You will get immediate pink, then water and then back to pink.
Continue to do above step at each and every sink, faucet, toilet, bath, shower, Washer, etc. Don't forget Washer and outside shower. You will have to switch out pink jugs 1-2 times as this will likely take 2-3 gallons.
Once ALL the lines are full, turn off water pump. Open several or all the faucets, showers, toilet, etc to release pressure. (I don't leave them open).
Take remaining pink stuff and dump enough to fill all the P traps and will get some in gray and black tanks. I use a fourth gallon for this.
Wipe out sinks and showers and see ya in the spring.

In spring simply put some water in the fresh water holding tank.
Find water pump lever that controls from fresh water holding tank to winterize. and put back to fresh water.
Turn on pump and rinse the pink stuff out of all the lines.
Un-Bypass Hot water heater.
Continue to use on pump or reconnect and switch to regular water.