My experience has shown that storing the fuel tanks dry is better than wet (except for Sea Foam, Fogging Oil, or ATF). Note the steel tank concerns for older sleds. Storing the engine itself with adequate oiling (again Sea Foam, Fogging Oil, or ATF) can greatly extend the life of bearings, wrist pins, and other engine parts.
If you take the vent tube off the steering gate (above the left footwell on a Viper) you can slightly pressurize the gas tank. Incidentally I use this method to fill the carbs in the fall, as it saves a lot of pulling on the cord. Do not put very much pressure on the tank or you will blow the fuel pickup connector apart. I usually leave the gas cap slightly loose so I can hear it leaking slightly. If you take the feed line off the fuel pump, then it is real easy to drain all fuel from the tank quickly. Siphoning the tank is ok to start with, but it leaves quite a bit of fuel in the tank. Enough to idle a sled for a half hour or so. Once the tank is dry, the carbs will still have fuel enough to get it started and oil the engine. You can replace the fuel pickup line on the fuel pump, and take the other end off and drop it into a container with ATF or whatever oil you wish to use in it. Start it up and run it until it you can't keep it running with the enricheners open all the way. Then pull it over a number of times. Drain the carbs (I take mine completely off and store separately), and you should be good to go. Be sure to close off all openings and lube and treat all parts as suggested above.