I haven't taken any pictures of the finished setup just incase it was a miserable failure..... as it turned out its works a treat

I had to re-machine the bushes down to get more clearance, as it turns out the more water that gets in the easier they roll, the water acts as a lubricant so now we have 1.5mm of clearance all round on the bushes....

20psi in the tyres makes it child's play to move the boat around on hard surfaces such as the carpark.
I found 5psi was really good in the sand but just a tad heavy in the carpark so I've settled on ~10psi for now....


advantages:
a breeze over a distance
doesn't bounce about over rough ground
easy on gentle uphill rises

disadvantages:
the rims are pressed 3mm thick steel plate so obviously rust in the future will be an issue, galvanised dipped may be the answer here
&
they are heavy when it comes to the placing or removing from the trailer


other than that....
all up I spent around 12 hours on the mig welder and lathe to make the hubs from scratch & modify the bushes to suit, otherwise it was just stuff that I had laying around....

cheap fix ...... not pretty but..... it works.....