Surely, there must be a better alternative for winterizing or is this not an issue when a system is winterized for only a year or two?
Yes there is a way to significantly reduce the amount of the AF used. It requires setting up the water system to make it easier to do.
Pump everything as dry as it can be.
Drain the HW tank and bypass the HW tank.
Disconnect the water line on the outflow side of the pump and open all the faucets. Use a compressor to blow out the lines.
Disconnect the inflow line from the pump. Use a compressor to blow any water back into the tank. Use a shop vac to clean up any residual water.
Connect a couple of temporary lines to the water pump and pump a small amount of AF through the pump. This is necessary because any water, even a few tsps can puncture the diaphragm in the pump.
In the spring connect everything back up to the pump, fill the tank and shock the system, see procedure on the Marine Sanitation forum here on SBO.
A little water left in the HW tank is not a big issue. There is plenty of room for it to expand when it freezes, it won't do any damage. Between shocking the system and the first long motoring session when the tank temp reaches 170° F any critters will be dead.
While it is nice to have the water tank bone dry, often it difficult to accomplish this. A little water will make the tank humid which can promote mold and mildew growth.