Was there any attempt to convert the 7.5 cm gun to a towed artillery piece? As I understand it, it was even better as an anti-tank weapon than Tiger I's 8.8 cm KwK 36, which was a conversion of Flak 36 which was pushed into antitank role. And while less powerful than 8.8 cm Pak 43, it would have been lighter and more mobile.
According to Wikipedia the 7.5 cm KwK 42, mounted in the Panther was also designated the 7.5 cm Panzerabwehrkanone 42" (7.5 cm Pak 42) anti-tank gun, when mounted in the Jagdpanzer IV. I suspect the reason is that the Germans did not need a towed 7.5 cm kwk 42. The 7.5cm pak 40 was good enough to take on most Allied armour. They also had 8.8cm pak 41 and 41/43 as heavier anti tank guns. By the end of WW2 towed anti tank guns were being replaced by SP guns. The 7.5cm kwk 42 was comparable to the US 76mm M1 tank gun and the British 17 Pounder anti tank gun. The US army had a plan to create a towed version of their 76mm tank gun , but abandoned the project. The towed version of the British 17 pounder was not popular. It was hard to manhandle and conceal. One Operations Research report into the engagements of the battle of the Bulge found that SP guns were much more survivable than towed guns. During the war the calibre,.length and weight of anti-tank guns increased to defeat thicker and thicker tank armour, The carriages needed to be bigger and heavier. too. As can be seen in this image showing the US 37mm, 57mm and 76mm US anti tank guns. The 37mm Pak 36 weighed 450kg for travel while the 7.5cm Pak 40 weighed three times as much - 1,400kg. The towed British 17 Pounder weighed twice as much again at 3,000kg. It took around twelve hours for the detachment to dig a pit big enough to conceal the gun and protect the detachment. The Germans did deploy the 7.5cm kwk outside an SP mount, but as part of static defences.
I believe they used some on the Atlantic Wall and in Berlin. This site also mentions use in the Westwall: Panther Ostwallturm | For the Record Some images of Panther turrets in Berlin: Panther turrets used a fixed artillery positions during the battle of Berlin a Panther turrets used a fixed artillery positions during the battle of Berlin b panther turrets