There's an article in the current issue of Good Old Boat on re-using shrink wrap (page 60). Basically comes down to how carefully you remove it, where you cut it, etc. Also, extremely unlikely you'll be able to get it drum-tight. Done successfully, it's cheaper than tarps, cheaper than a custom cover and cheaper than neglecting your boat all winter.
s/v Grey Goose
1977 Pearson 30 #995