I keep mine on a sack barrow when not in use. Got a bit of ply screwed to the top to clamp the engine on and it's handy flush it and wheel it into the corner of the shed out of the way. This is a 6hp engine for my dinghy.
Snap! - horrified by the price of a proper outboard trolley for my tender outboar, I got a sack truck from Screwfix for around £25 - as you say a bit of wood soon sorts out the mount but the big advantage is that the base carries the fuel tank - no 'proper' outboard trolley I've ever seen has any means of carrying a separate fuel tank. I thought it would go rusty pretty quickly but it's lived at the harbour for 4 years and whilst there is some rust it's got many years left before it becomes unserviceable.