My hypothetical tank would have the same frontal armor as Panther for less weight and side armor would be comporable.
Reaching an arbitrary weight isnt really the point thogh, my main concern with Panther is the ratio of armor to weight. They could have gotten a lot more armor or a lot less total weighth and complexity with a bit smarter packaging. So at 45 tons it would have more armor or have the csame armor at a ligher weight.
This tank armed with an L70 or L48 would completely dominate the T34 just like panther but would be far more numerous. Also it wouyld replace the Pz4, which was very hard to manufacture - taking almost as much time and money as a Panther..
This type of tank wpuld give a lot more german heavy armored glacis and long 75mm armed tanks into the field than really was the case. There is no scenariob whewre this is bad for the german war effort.
Oh and Panther D really wasnt a star at Kursk, im sure GTO can quote you the enormous losses due to malfunctions, enemy weapons etc.. But by the G series they got most all problems worked out but Panther was never really capable of long tactical marches. It's kind of ironic but I think that the USA was better off with Shermans than with Panthers in 1944 considering the type of warfare the US Army was waging - especially patton.