u guys think so narrowly when thinking of balance suggestions. its quite true its tough to balance between these high value static emplacements and the '2 click counters' that destroy them. personally id like to see both howitzers get their range reduced by 25-33%, their cost reduced to 400-450, pop reduced, unable to be built in base sectors and maybe drop the number of shells fired down just a tad.
i think this pretty drastic change would force players to build howitzers in significantly more forward positions than they are now to use them offensively (which at the same time will leave them vulnerable to pushes from the enemy), or they can choose to build them further in their own territory and use them as a defensive unit instead. the decrease in cost means that having 2 or even 3 howitzers is feasible, and significantly reduces the impact of a single stuka divebomb taking out your investment.
These are the best ideas so far. I had a similar conversation with some friends yesterday. Reducing the range, also makes it possible for mobile arty to get into range of the piece a lot easier, and soft counter the thing, should one choose the wrong doctrine.
Only one problem remains if you do this... CAS. All the other 2 click counters become an even (ish) trade off in the scenario of your changes.