You will find there is nothing cheap or simple about raising deer., haha. I see what you mean in your post, but I agree with others, there is no possible way it would work in my opinion. At least not to a point I would feel safe taking my eyes off them. I don't even feel good about my fence post unless I can sink them at least 3 feet in the ground. Deer are a whole different species, and even the tamest ones can spook if a simple paper bag blows through the fence, let alone see you dissassembling and reassembling a pen. Also, When deer spook and crash into a fence, they can hit the fence with the force of a small car and can pop staples and twist wire.
I mean No offense to you at all, you can't learn if you don't ask questions, so I respect your question and wanted to answer with my honest opinion based on 8 1/2 years of raising deer.
Although it won't be cheap, your best bet is to fence in the whole field, and divide it 2 or 4 times (depending on your field size) and put a gate at each corner and do pasture rotation all summer.
If you do get into raising deer, I wish you best of luck, and have fun.