where do you plan to sail?
a few years ago we built a whole series of them , and got them to the pont where we could start catching blokarts in lighter winds.
that was the point where we realized taht standing on a board on a salt lake at 40kph was a really stupid thing to be doing. My version % is sitting on the same rack in the shed for the last 2.5 years , not game to get back on. look out for alloy 12" prm wheels as theese tended to be the best. 16" tend to act as a foot trap. there are plenty out there with decent sealed bearings that will take a 12mm HT shaft, thats the min diameter you need.
pad up , be careful, god bless