Chucking this here in case it's useful for someone.
Given: parking hassles last holidays; some of my sailing spots are not accessible by car; I have an LT, which is 'light' but too heavy to carry long distances - have thrown this together. Cost approx $60-70, mainly for Bunnings trolley and the pvc (pressure rated). Had some other bits lying about.
I considered making something lighter just out of pvc, with lower clearance, but I wanted the clearance this one gives. Means I can centre the trolley more, making things lighter. The weight is not an issue (maybe 5-6kgs), and it should last. After a trial, the main issue with having the board higher (rather than between the wheels more) is that it has to be tied down more securely otherwise the trolley shifts on bumps.
Only thing to add is some sort of netting or maybe a cut down tub in the 'v' so I can carry stuff under the board.