Re: sand and sideways
In my experience, I've shut off the fuel-petcock at the tank, emptied the carb-bowl, and replaced the gas-cap with a rubber surgical glove secured with some fat rubber-bands. To be on the safe-side, lay the bike on some old towels on plastic garbage-bags.
Now, getting BACK from the spot: is this motorized bicycle a pull-start? You may have problems starting your engine if it's manual-clutch, even @ low-tide.