I think the device may already exist.
There is a guy who sails at West Kirby who walks to the lake with his kit all packed up on a trolley.
Basically the rig components are packed up, laid on top of the board with a strap to secure. The trolley which is a simple vertical 'V' with a pair of large beach type inflated tyres is then placed under one end of the board and secured with a strap.
You then simply pick up the opposite end of the board and walk.
The 'V' shaped trolley folds flat for easy storage. The whole thing must be no bigger than the old fasioned shopping trolley for taking groceries home.
Alternativly there's this one available from Decathlon
http://www.tribord.com/EN/tr-400-trolley-3557255/