Rivers, Bridges, & Gunboats

I want to suggest the addition of rivers to COW.

Throughout history, navigable rivers have been a key geographic feature of key importance in times of war. Rivers should be added to Call of War to reflect this. I think this feature would add a nice new wrinkle of strategy to the game.

My idea of rivers is this. Large rivers that are traditionally considered navigable waterways, like the Amazon, Mississippi, St. Lawrence, Rhine, Danube, Volga, Yellow, Yangtze, Mekong, Ganges, Indus, Euphrates, Nile, Congo, etc They would be represented as blue lines running across the map. Land route-river junctions will be marked with a circle like where two sea lanes intersect in the ocean. Rivers are considered neutral territory, like other waterways on the map. Any army crossing an unmodified river will act as if it is making a 0 distance sea crossing (3 hours to embark, 3 hours to disembark, 4.5 on enemy territory). Rivers can be traversed by transport ships, but not other Naval units (more on that later). In addition, local ports can be built at river intersections to reduce embarking times.

These rivers will have a new ship patrolling them: the gunboat. A gunboat will be a small and relatively fast ship that's slower and has less HP than destroyers; but is cheaper; does more damage to ships. ground units, & buildings; and has a modest attack range of 25. This ship will serve as a easy way to escort convoys down rivers, defend coastal provinces from landings, and harass enemy units near or the river.

There will be a new structure to make river crossings much faster, the bridge. The bridges is a structure that can be build at a junction can be built between a river and a road. Like ports and naval bases, a user may pick the location of a bridge if more than one location exists inside a province, though a player is not limited to one per province. There will be several tiers of bridges, each one having a different effect on the river junction:

1. A level 1 bridge represents a pontoon bridge. It can be built very quickly (30 min) and inexpensively, but has very little HP (5 or 10). When a unit enters the river junction space with a lvl 1 bridge, the unit must stop for 4 hours before it can move off, and does not convert to a transport ship. During this crossing time, a unit is considered stationary and can't attack. If the unit tries to move off the bridge the way it came, it must wait for 4 hours minus the time remaining on its crossing (same as embarking/disembarking).
2. A level 2 bridge represents a small temporary bridge. It cost a bit more and takes a bit longer to build (1 or 2 hours). takes 90 minutes to cross and as a bit more HP (20 or so). To build any bridge lvl 2 or greater, a player most control or have "right of way" in all territories the bridge connects to.
3. A level 3 bridge represent a large permanent structure that can accommodate heavy traffic. Units can cross the bridge at their normal movement speed with no delay. They take longer to build (6 hours sound good?), cost more, and is much more resilient (I'd say 50 HP).
4. Possibly a level 4 bridge level that costs more and has more HP than lvl 3, but is otherwise the same.
5. A level 5 bridge is a highly fortified structure. In addition to high cost and massive HP it also prevents non-right of way ships from moving past it on a river.

I think the addition rivers, bridges, and gunboats will add more strategic nuance to the game. Since crossing a river in the face of a hostile army leaves an attacker so exposed and low level bridges are pretty easy to destroy, players discourage players from doom-stacking and advancing across a single point. Defenders will be free to wail away at advancing forces while they are unable to attack back. This may encourage the use of new strategies like using paratroopers to secure the opposite side of the river to build a higher level bridge, or using a mobile army to get to a river before a slower enemy. Rivers also give infantry armies a faster movement option in some circumstances, as transport ships typically move faster than most infantry units. However gunboats and fortified bridges make it less practical to attack up a river without a stronger fleet of gunboats at your disposal. The importance of bridges in crossing rivers quickly also makes stat bombers and rockets a bit more useful, as destroying a bridge could significantly delay the speed an enemy could move in reinforcements.

LMK what yall think about it. How would yall adjust the different units costs and capabilities?