OK sappers have been asked for before.....
That in the absence of targetable sappers as alternative load outs to grunts.
That grunts may be set to trooper or sapper in the vehicle/ac weapon select and then released to inflict damage upon the nearest ( not yet destroyed) enemy object. (Town bldg, hanger, ammo bldg, fuel bldg, radar, supply bldg, soft gun)
This avoids a little of the frustration incurred when someone valiantly turns up in his/her M3 to find its all been a waist of time...... the town/field is just not ready. So he/she switches his/her troops to sappers and lets them loose to do a little damage.