Its not that hard to make a trolley cradle, especially for a boat without too much bottom curvature like a Spence 7, so you're probably best off making a new cradle for whatever trolley is handy. A Firefly trolley with a new cradle would be fine, or an RS200 for that matter. I reckon a Firefly would be a very different shape cradle though. Nice thick artificial grass (best padding) helps with a lot of inaccuracies in cradle building. A cardboard template, some 6mm exterior grade ply, a bit of stripwood and you should be away. Make sure you err on the side of having more weight on the hog and less on the chines and panels, but keep it as even as you can.
