What about this one instead:
- Brace is removed
- Instead, mortar pits get an ungarrison ability that releases the mortars from the mortar pit
- The mortars can continue to fire and operate outside the mortar pit, but with limited range and efficiency (at sub-soviet level)
- Each mortar pit mortar requires 1 mortar squad garrisoned to be able to operate
so you mean the actual emplacement is like a trench but for mortars only? Why not just do a comeback of mortars being able to get into trenches?

But I dont see why the mortar needs a range buff, if static. He is stationary yes, but also protected from easy enemy counter mortar wipes. Weapon range across 50-75% of the map just seems cancerous to me (like the current mortar emplacements or 120mm mortar)
Edit: The insane range of some mortars is one of the most important reasons why mortars are so fukin Overkill in this game.