LaSombra, You certainly wouldn't need to get the tractor into the moat area as that would be only for the chickens. Did you mean get the tractor into the garden? I have two gates going into my garden - one is a walk thru and the other is large enough to be a tractor through. I'm putting my moal to run along three sides of the garden and each end is right at a gate. So it basically runs between the two gates.
I have completely redone my garden this year and turned it into a 'potager' and don't plan to till it anymore.
I brought in composted manure and built up the soil in the areas I planted in. At some point I may line them with either boxwood to define them or bricks or something but for now the soil is just mounded.
My plan is to add to the soil every year with my own compost. And I'm hoping to be able to have a chicken tractor that I can move among the paths. The chickens will then weed, till, and fertilize for me and at the beginning of planting, I can scoop some of that nice tilled path dirt up onto the planting beds.
Even without chickens in there, I wouldn't till. I would keep the paths weeded and then bring in compost and add to the planting beds as needed. It really keeps the weeds down if you don't till the ground, which exposes weed seeds to light. I have friends who have been using this method for years with great results.
Here is a not-to-scale diagram of my potager garden. The overall size is roughly 40x60 but one of the 40' sides and one of the 60' side are slightly shorter.