Hm, it sounds like a good Springer with plenty of buoyancy is the optimum choice as it will also allow you to fit gizmos like arms etc should you feel that you need more comprehensive rescue equipment aboard to help your fellow sailors.
Do you always attend meetings Jeff? I ask because the weakness of a rescue boat is if the builder cannot always attend a meeting thus leaving sailors without support. You as a club may need to build one or two extra rescue boats held by the members who regularly attend, or arrange for an assistant rescuer to collect and return your boat.