Wow, the choice of 98, 100 and 110. Safe to use? Damn right, I wish I could find it, I'd use it. Read this site about Sta-Bil gas stabilizer,
http://www.parkeryamaha.com/fuelconditionerqanda.aspx . It will give you mixing ratios and will keep your gas good for a year and a half.
Raise the top to keep it tight and stretched, folded will permanently instill creases and possible damage.