I got one of these ;
http://www.seaswan.co.uk/Full-Engine-Cover.html
for my 2.5hp - just to stop the scratches - the handle can be used through the cover so its easy & I only need to carry it a few yards.
It also stops it getting dusty / dirty when its in the garage & makes it less ' obvious' as a nice new motor when its on the tender - & hopefully less liekly to get swiped !
The prices of some of the bags are very OTT in my view. These seem to be a goodbet - mine was an ebay effort - worth keeping any eye out.