Phil,
Consider using astro turf to pad the cradle. Doesnt hold water next to the hull and avoids the danger of grit & sand getting in there and scratching.
For the trolley design also consider if you want to lash the boat to the trolley (amidships and bow) and tip the whole lot over together when rigging. That is our preference, like I14s do I think. If you do, try not to make the craddles any higher or the trolley any heavier than necessary. We tie a bag/tool box to the mast tip when we tip over to weigh it down prior to the sails going on.
35? Bloody hell! I thought you were much older than me.
P