You definitely need to wait until next year before looking, the east, west and Sussex prem are looking to merge into a pyramid table to feed into 3 divisions of the Sussex prem, therefore Sussex prem div 3-6 will merge down etc...so depending on teams rankings a div 3 team could be restructured into div 5 ...and there being more leagues....
Have you not thought about West Sussex league? Plenty of good clubs, our 1XI are about to get promoted into Div 2 (scaynes hill cc, 18 min drive from brighton). But if your looking to play higher, I know several people at Cuckfield (Jeet Ravel, NZ Test opener is playing for them this year), Horsham, Ansty would be my personal advice, all a 15-30 min drive from Brighton.
We have just signed up a Sussex premier player as he fell out with the team, just wants to enjoy his cricket, had one social night with him and he paid for tour the next day.
We have a few irons in the fire to get back 3 Sussex prem players who could finish off their careers with us 😊