As mentioned by scott, have a look over at blueheronkayaks. a few have been made. I have seen ski carted around on small cars. Trick is to tiedown at front and back.
Main consideration when building a ski is the loss of structural integrity with the open cockpit.
i'm building a hybrid ski. S&g hull with stripped deck. The hard chines feel strange but shouldn't be a concern on flatter water. I suspect that it won't be as well mannered as a normal round hulled ski in the rough. Search BoofHead65 on youtube if interested in progress.
Cheers