At my club reciprocal membership does not include using a pen or having a a boat on the register (which means you can't use the hard standing area, launching ramps or use your boat in a club event). Hence why the cost is half the ordinary membership. However you do get a key
Also note the nomination fee can be expensive, over $2k at my club.
I was also thinking with regard to pens, check out whether the various clubs allow an overhang. Some clubs allow up to a 10% overhang, which means a 11m (36ft) boat can fit into a 10m (33ft) pen. Other clubs / marinas strictly enforce no overhang.