decent chunk of the yard "unusable" for vegetables (most of which apparently want full sun all the time)

I think maybe some sort of elevation or having a box with soil set up in the air or wall garden that anticipates the sun movement would be able to help you plant.

they ate literally all the grass to the point where it was unable to regenerate and just completely died.

Similar thing happened to my grand father's home. The lush grass I once knew gone after they started breeding ducks.

I think the part where there are so many things to do and possibilities about the garden is what attracts me. The process of building it is more important than the harvesting. I used to work on a herbal garden until I didn't have the time to maintain it and snail ate up everything :/ still fun to do for stress relief.