Even if you use recon 100% of the time, you cannot keep sight of the sturmtiger as there will be lapses in coverage. Thats an unrealistic situation, and doesn't counter the sturm simply slightly delays its impact.
If it keeps this damage/aoe/range, it needs to lose its rocket phasing through objects (firing over small objects fine), if it doesn't it needs to lose one of its buffs.
As i've said there's 2 units that already have mechanics to deal with this, no reason why the sturmtiger couldn't adapt similarly
One ability costs 90 munitions and can be planted by the most basic units in the game, able to wipe your squads under the 5 min mark. The other unit costs 160 fuel arrives in late game and is doctrinal and is risky because a panther / p4 /kt might have been better.
Since the Sturmtiger requires a large amount of resources it should also take a significant amount of resources to counter it.
You don't need to have a Recon plane permanently flying around, all you need to is to recon before doing a push.
On map arty wipes squads all the time without warning and costs less. Always those double standards.