There are pkgs offered by aquarium size, but IMO
they don't distinguish between new and existing tanks. For instance the recommended amount of snails for a new tank would starve. The crabs might have a hard time too. So I would add just a few for now. Consider 20 electric blue hermits, 20 scarlet reef hermits, 5 turbo snails, 10 astreas, one brittle star (lots don't like the greens - more agressive by some accounts), 3 cleaner shrimp, and if you're so inclined (since some don't trust crabs), a couple emerald green crabs. Also consider 10 peppermint shrimp. I'd do some research on cukes before you decide. Some can be toxic to the tank if they die or get bothered too much. I'd research'm and wait until your new tank settles in.
Compare the list above to LiveAquaria's recommended cleanup crew and I think it's still a lot loswer than thiers. Then you can look at nassarius snails, other neat snails, other stars, and stuff like that as you grow. But IMO
, you've got enuf rock for the smaller (for now) crew to forage. Assuming you have fish too where the "crew" can get leftover food? If not, you may have to feed the crew anyway until then. Sinking pellets for the crabs and shrimps for starters.