Tactically, the application of German rocketry was becoming more and more a substitute for artillery, which was relatively cumbersome to deploy, unless it was a genuine SP gun like a Hummel for example,and more vulnerable to air & counterbattery, the '251 series mobile launchers added real punch to the infantry support as well as some comfort to counter large infantry & massed tank attacks on the Eastern front by this stage.
As far as I am aware the appendages found on the Panther(Poland) and the pictured one on the Tiger, were in the Eastern Theatre. Makes more smarts to use masses of rockets on masses of tanks, infantry & artillery the Russians were favourites of.
The concept of "wasting" a tank as a rocket carrier can be looked at also ;
The effective range of the Panther(or Tiger 1 ) gun we can agree is easy 2000M.
Line of sight of course to be on target.
Defensive tactics mean your tanks are not cavorting about looking for the fight, rather hiding from the air supremacy & hitting the enemy as they present, preferably at the greatest distance possible.
I contend that this form of expedient 'ersatz' artillery gave indirect fire to reasonable area saturation- just like a salvo from a 251, but with the added bonus of having far greater lethality on the survivours of such a salvo(s)from hidden rearward positions that they simply could not get conventional artillery to do at the time it was needed.
IF this system was employed on a tank(s) as well as the 251's it is surely plausible that the same swivels & crate clamps were used, but on the stronger mystery mounts as found on the Panther & Tiger, fired the same way & certainly reloaded the same way by the very support vehicles that carried them as offensive ordanance anyway ??

