I live, fish and guide on cape under capeflyfisher dot com. End of May is fantastic and the fish are very willing due to migration (they need to load up on calories).
BTW there is a clave going on with fishermen from all over converging in the Chatham area, sorties to anywhere from Ptown to Woods Hole not out of the question. May 21-22 weekend, many arrive Friday and stay Monday.
Spey fishing for stripers works where you have current and fish are feeding on the swing... but a single handed 9wt is more versatile. Some situations a two-handed overhead rod capable of throwing some grains (i.e. over 500) for distance will get you over the surf and into big fish where the other two approaches are miserable.
Given one rod, make it a 9ft 9wt; one line make it a sinking or intermediate (for May). Fly doesn't really matter in May unless you're going for trophy herring chasers or sound-side squid eaters, neither are likely on your first visit.
You'll get a lot of religion about floating lines and jungle cock on some sites, but personally I reserve that level of sanctity for native pacific steelhead
If you are determined to Spey fish for spring stripers, drop me a PM a week or two prior and I will give you several spots where it is best suited, and the times of day to fish them (tidal).