Sure but why not unlock bew variations for it
Std Flux and locus variations of wide rang,
Adv normal precision(small radius big boom) ,
Proto long distant (extended travel time and distance)Normal and short range
And you can mix and match for different style ex. Long distauwide range flux or short precion locus
should not be refilable from nanohives but can fron depot

If they did create a "mortar tank" I think it would look like the minmatar tank on the vehicle concept sheets from fanfest.

http://i.imgur.com/xSxlftZ.png (it's the third colum from the left in the middle row)

The should launch a missle that is packed with cores from the plasma cannon it should do twice as much damage as railguns but consume a high amount of energy. Then skilling into Minmatar tanks should lower the heat consumption this ount really put a hurting on railgun snipers. There should be no damage drop off due to distance and the impact should show up on the minimap.
This way you can look at the target its distance will be displayed and minimap would give you an ideal effective range.

Why don't we just go ahead with the trend and make the mortar another AR variant?
You know, because we just found something the AR cant do.

A read a dev post somewhere that a variant of the mass driver may eventually be introduced like a mortar weapon, with a very large blast radius and maybe high damage but inaccurate. Basically a few cheap kills every 5 minutes like with a LAV. Although another dev also stated (if I remember correctly) that another new equipment item may be introduced eventually that acts like a temporary and stationary shield against weaponry to prevent orbital strike kills. (that equipment may also be intended to counter mortars and act like deployable cover in open area maps.

i know but i still dont know how a mortar vehicle would look like in dust..but itd be pretty cool to see one...

i think it should have a cooldown type rate instead and the unlimited ammo

where u have an extremely low rate of fire... good damage out put and great range but would suffer by being extremely weak..and fairly easy to take out..

in first i think if ccp were to make a vehicle like this it would require a lot of testing and tweaking in order to get it just right where we want it at...

Also i really think the easy way to balance this weapon is having it as a vehicle with limited ammo and slow speed. I would basically say the reasoning for the slow speed would be the extra weight of the ammo and mortar tube.