Well, it's taken a while, but I've finally made some progress with this. Did a 'dry run' fitting today of the winch cradle and receiver and so far, so good :)
The rear door will just open with the winch in place, which is nice.
The solenoids are going to be mounted inside, in the space where the offside jump seat would be.
Next jobs are to paint the cradle and receiver before bolting it all together properly and to sort out the power cables. After that, I've got to get a bracket for the front mounting made up.