How small could a ship carrying the Schwerer Gustav gun be?

What is the smallest hull that could carry a Schwerer Gustav-caliber gun?

Probably a 12,000-to-14,000-ton, roughly 200-meter monitor-like ship with a fixed rather than rotating mounting.

The estimate starts by comparing the gun's length, weight, and recoil problem with ships built around 15-inch weapons. The Gustav barrel was nearly 48 meters long, far exceeding the dimensions of an ordinary naval rifle. That leads to a vessel of roughly 200 meters and 12,000 to 14,000 tons. Even then, the weapon would probably require a fixed mounting aimed by turning the ship rather than a conventional rotating turret.