So far, I've been alternating my setup for ?-4 between 2-1-2 and 3-1-1. Bottom tent would always have my team 1, to activate the magnifying glasses, while middle squad would have Dipladenia to race through the webs.
The nice thing about 3-1-1 is, that at completion, one of the teams will circle through the pests top left to gather some extra coins, but the extra bottom unit with 2-1-2 means I get a shot at another fast team taking the low route and possibly grabbing a chocolate or solar node. So I'm still not sure which I like better.
I actually wonder whether there's anything extra hidden below the nests in the top left, but I never managed to get through that part in time.