Going by those very sparse rules then Acrylic should be ok but watch out for axes/hammer bots.

I cant see any issues with the design in general. Given there are no weight or weapon limits you are free to do almost anything!

As the arena is so small its most likely to be a pushing war so make sure that your lifters front edge is as low as possible. I would personally say that the front lifting edge should be the same width as the whole robot so that no one can get in and lift you up unless you go round the sides but its up to you.