Got a response from Ribcraft. The config of 5.3 with 2xdouble Jockeys, A-Frame and underfloor tank plus DF90, baattery and cables is 701KG (estimated). This only leaves 100KG for the standard 800KG load capacity on the trailer.
100KG is not a lot when you need to add:
- 90l Fuel (at estimated 700g per litre)
- Anchor, chain and warp (estimated 30KG)
which only leaves a few KG for:
rope, gear, flares, fire extinguisher, oars, tools and spares, toothbrush etc.
So - trailer appears to be a bit under-rated for a normally laden boat
Maybe the RC is unusually heavy but it seems you have to go a good bit over size on the trailer to get any more carrying capacity.
I do plan to weigh it using Polwarts clever scheme but I think the estimate is fairly accurate.
(Edit - I have a 50, not 90 but also an aux, extra fuel and a dingy which is same weight as 90 - 90 was for illustrative purposes only as a typical installation)