On my current sled (SDI) I put stabil in the tank and filler up with fresh gas, then let it run through the system and leave it till next season. In the fall I'll siphon about have the gas out and put some more fresh in but thats it.
I see that you have a 99 670 Ho which I know has a fuel shut off so I would put the appropriate amount of stabil in the tank for the amount of gas that you have and run it some. Then I would shut the fuel off and run it till it won't run anymore. Next you can either pop the bowls off and dump any leftover fuel out or just leave it. On that style sled I used to just leave the bowls alone and I never had any type of buildup but some guys like to be 100%