[DSII] Infantry Mortars

What mechanic are you using for infantry packed mortars?

I think it _might_ go like this.

70 pts (20 pts infantry + 50 pts light artillery)
+cost of ammo.

Moves as infantry, may spot for itself.  May _not_
fire suppression missions as they don't carry that
much ammo.

The spot for itself means no delay between designation
and splash so units do not get to move.

Does this sound good or am I way out in left field?

I've found under light RAM mortars that they may be
carried by infantry but have seen no other rules.