Ah, a classic catch 22, can't catch 'dem bones after Labor Day, can't secure base of operations for the clave until after.... hmm, we need some creative thinking here.
What about a mid-week event? Might be easier to secure the Washburns site(s). Less vacation-type traffic (on and off the water). Puts more emphasis on the ability to juggle work schedules.
One-day Bone-Blitz. We'll boogie 'till we drop (maybe have a mid-day onthewater lunch break and retire to a pre-arranged watering hole and carbo station for a recap of the day. Choice of site contingent upon the quality of their wasabi. Less logistical pressure without the campsite but a decided drop in the potential comraderie.