Is it possible to remove land bridges?

I first thought that land bridges were a good thing, but that was back when I thought that I could block them with ships. It turned out that this is simply not the case: it in't possible to position a fleet directly on the crossing point. You could place two fleets next to each other, on both sides on the crossing, but this will do nothing whatsoever, armies can just march across without problem. I dislike the way this makes navies even less useful than in unmodded RTW.

In RTW where the AI is too incompetent to actually use ships to invade, land bridges might be a necessary evil. But I'm now playing 0.81 with Barbarian Invasion and I've seen reports of AI using naval transport in BI, so I think that it'll make for a better game to let the land bridges go.

Does anyone here know how one could go about modding the land bridges out? Would such changes be savegame compatible?

It is possible through changing the 'picture' that dictates the shape of the landmasses. You would have to change several files and delete the map.rwm. 100% not savegame compatible.