I think that depends a lot on the slip as well, a good well balanced trolley does not make the GP any lighter. I must admit I would suggest one of the more modern and lighter plastic bath tubs.
I would also check out the club that is going to be used first as well as opting for a class that is popular there may give you opportunities to both crew for others and get crews, both of which will help you improve your skills, and add to your enjoyment.
