A simpler way of doing this is to allow current HAVs to have a new large turret called an Artillery piece.

How real mortars work:

First, a Call For Fire order is submitted by a unit, usually a squad (which is usually 13, not 4-6) at which point a mortar section sets up. Usually anywhere between 3-5 guns make up a section, depending on how well equipped the unit is. Once they have set up, usually a minute, they get comm with the unit calling in the strike (Unit ABC) Usually the format is "This is Unit ABC, we are at grid coordinates (whatever) enemy about (whatever distance) to my (whatever direction, given in degrees or mils) Example. "This is Unit ABC, I am at grid coordinates 1234 5678, I have enemy contact 500 meters to my west, 270 degrees." Based on this information, using maps and a compass, the Forward Observer (FO) does some math magic, and gives a firing solution to the guns, which then dial the solution into the mortar guns, and then the strike is sent off. This takes about 5 min from start to finish, assuming something doesn't go wrong (it usually does)

To this end, I would suggest making the vehicle mentioned be unable to fire without a firing solution. Have it load multiple rounds, or have multiple tubes, and require someone else to have a piece of equipment that lases a target. Once a target area is lazed, The mortar(s) fire at the target. To balance this out, have a long time-to-target, say around 20 seconds or so (Modern mortars are anywhere from 15-30 seconds, depending on how many charges are on the round when its dropped in the tube) and have the vehicle need a recalibration and loading delay, perhaps requiring the vehicle user to get out and manually load the tube or tubes, but in some way require that he cannot immediately fire another salvo. Maybe a 1-2 minute delay. HAve the mortars deal 600 splash damage, no direct damage, in a 20m radius (modern mortars have a kill radius of 35m, so this is lower than normal) Give it a max range of 1.5km. (modern 60mm mortars can reach out beyond 3km, almost to 4km)

This would make a great asset to coordinate teams, with squads getting support beyond an OB, and the enemy can use an OB/Railtank/Whatever to destroy this asset. I would add these in after the maps have opened up and we have larger fights, 32v32 and such.

Posting this from the other mortar vehicle thread, for exposure.

i hate to be that guy that says this is what its like in this other game but here goes

in battlefield 3 you can in no way setup a mortar while in your own redline this is to prevent tham bombarding the enemy from a completely safe location if mortars of any kind are implemented i suggest CCP do the same or we will have something even worse then redline sniping/rail tanking because mortars can kill you whilst hiding in cover

so no mortars in your redline is a much needed feature if they where to implement this
i would suggest that these MV's need to setup before firing rendering them immobile and after firing they must remain immobile until they have reloaded to prevent hit and runs rinse and repeat lol

but overall i like the idea +1

I see your reasoning. Maybe as a balancing factor, the large mortar turret would require a lot of CPU and PG which would not leave any room for secondary weapons.