But you can't. If it were that simple, it would have been done.
The Jackson is what it is because Relic designed a faction with one nondoctrinal AT vehicle. The Jackson does everything because any vehicle that counters the Jackson counters the entire USF motor pool.
If you want to make the Jackson more geared towards killing heavy vehicles like the SU-85 or Panther, you need to add another TD to the nondoctrinal lineup to handle the anti-medium work.
Honestly I think we're here because of the P4. If the M4 was better at countering armor, or if bazookas and the M1 didn't reliably bounce off of it, everyone wouldn't be going for jacksons.