Our eventual plan is to have ground-level planters in a U where the opening in the U is the door. The first step: build a prototype and put it in place at the very end of the greenhouse opposite the door. The weather "co-operated" by being sunny and bloody hot. Building in south-facing yard becomes a somewhat sweaty experience.
Planter Mk1 is a very simple box, about 87"x31" and 18" deep.
Building the planter outside is a plus for avoiding the heat but putting it in place becomes a little exciting. It's hard to rotate inside when you built something almost the full width of the structure. Still, eventually the damn thing slotted in.