If you have the elite membership just cancel the date. No need to attempt to sell.
If selling is a must then post on Facebook as there's more foot traffic.
Proper clip on and rearset adjustments go a long way. I strive to ride every session and 95% the allott time. I do get fatigued on day 2 after lunch though and come in usually so I can start packing for the trip home around 4pm.
A good night's rest and staying active between lunch helps with...