I agree to an extent, but the sausage dam is only effective up to the point where the sausage starts to get eaten.
The instant the dam is broken, that then causes a veritable tidal wave of baked bean infested tomato sauce to head inexorably towards the pure golden yellow of egg yolk. I've tried in vain to divert the flow with a rasher or 2 of bacon, or even the crust of a fried slice, but it just won't hold it.
Clearly your beans are far too liquid. Even with a premium brand of beans it pays to pour off some of the excess liquid before cooking. An undercooked beany soup is a disaster waiting to happen. The correct consistency of beans is vital, a tablespoon of beans dolloped onto the plate should settle while retaining a slight convex shape, the liquid should be thick enough and in small enough quantity that surface tension holds it close to the beans.
Further given you are having the beans you must decide which components of the full english are going to be eaten with it. Clearly you are happy to have beans with sausage and at least a corner of your fried slice. I am a big fan of black pudding and beans, and hash browns and beans, adding either of these to the plate will give you more options to both contain and mop up your beans.