Eastbourne Boro used to hold the final, Bognors ground would be pretty decent as it arguably has the best pitch outside of the AMEX in sussex.
I went to a final years ago (probably 35!) to see a friend play for Lewes against Albion reserves at the Goldstone. They had a great day out and there was probably a few hundred people in the old West stand cheering them on. Not sure if it was at the Goldstone because Albion were involved or if that was the norm, but the Lewes players thoroughly enjoyed it despite losing.