Check out C&J, they do a few models on rubber. I don't think I've ever seen a C&J balmoral on rubber though.
I've worn shell chukkas with a suit, and I think it was appropriate. I think it would totally depend on the suit and the shoe, in your case. Ultimately, compromise is often necessary. It's not like someone will punch you in the face for wearing suede chukkas with a "smart" suit.
On edit; what about overshoes? Swims is a good brand.