We had a GC that wouldn't supply toilet facilities, instead suggesting we use the nearby sandwich shop.
I sent him a Change Order for sodas that the guys had to buy to use the "Customers Only" restroom. He refused it...so.
We all piled into a van, went to his personal home nearby, beat on the door at 6AM, and when he answered in his bathrobe, asked if we could use the bathroom.
(Not very businesslike, but he put facilities on all the jobs thereafter).

I'd get the Porta-Potties, (the deluxe models at that) and charge the markup and OH.