That 5ft does not match the rest of the map style. I'd personally go for a different font and put it in black instead of white. Plus, it might look better in the box next to the skull. But that's me.
I like the third one. It is exciting, and bold, and the tail of the 5 doesn't dip below the shadow.
I love the texture, but the issue that springs to mind is the scale of the map. How wide is the river? How large is the bridge? What if you were to do a turf texture for the shores and the bridge is a stone construction? That way you could use either rock tecture without it overwhelming the whole peice.
You must have missed the scale in the border at the bottom . The river averages 40' wide & the bridge is 45' x 10' spanning a slightly narrower part of the river.
This could be done with any ground texture, but it was supposed to look bleak and lifeless. A horrible prison in a terrible place.