You're advocating for an unit to gain enough range to be untouchable by AT guns,
There's a reason units like the Katyusha, Pwerfer, and Stuka have very low armour, and very low health. If you're forced to dive to deal with them, then it should be expected that you can actually kill the thing when you dive. It takes three shots from either the P4 or Panther to take down a Scott, necessitating a trade in most cases. Coupled with the smoke you'll have a practically unkillable artillery piece, that has a comparatively low cost compared to the vehicles expected to take the risk to trade for it.
The Calliope has the same absurd strength, but is at least toned down due to its cost and the fact that it's doctrinal. (Despite this the Calliope's survivability is a point of contention)
If the Scott got more range, I really can't see why it should keep its 400 HP and 70 armour.
because M8 is Howie on track not Rocket arty. For god sake. You cant compere a subtain indirect fire with Rocket Savlo.
Your Pz4 can make a short dive to force it retreat and keep bleeding USF inf. Of couse Axis players wont have a ball for that anyway.
Thinking about all USF armor can be killed by easy dive from every Axis armor is unaccpetable !