Your wheels look like the modification I made to my MBS by adding spindles that fit over the existing size spindles so I can run with larger tires.
The bogging down in the sand is no more.
The deck seems really low on your board, though. Have you ridden it in grass? Seems you'd be dragging in the grass a bit. Looks really cool, though!
V
http://www.chicagokitesurfing.com