> It would just have been amended out. Look at the debt ceiling.

The debt ceiling isn't in the Constitution, and, as such, doesn't really demonstrate anything relevant. OTOH, all wars are characterized as defensive, and the US has usually been at war, particularly in the times of concerning deficits; aside from—if construed to require formal declaration of war for borrowing—making declarations of war more common, I can't see that the proposed restriction really would have changed much even if it existed and weren't amended out.

> You can't really stop a government from borrowing except by taking away the power to print money

Taking away the power to print money prevents monetizing debt, but it doesn't prevent borrowing (it actually eases borrowing, which is one of the reasons for having independent central banks separating monetary from fiscal policy; the degree of perceived risk of debt monetization makes borrowing more expensive, so controlling that risk facilitates borrowing.)

Yes, I know the debt ceiling isn't in the constitution. My point is that when faced with a legal limit to borrowing Congress always voids it. It would have happened a long time ago if the restriction was constitutional in nature.

Congress can't amend the Constitution, and it takes a much higher bar for them to even propose amendments than to pass normal legislation. So, no, you can't use the debt ceiling (which isn't even nominally a legislative limit on Congress—which would be unconstitutional, as Congress cannot bind future Congresses—but an additional limit on the executive alongside budget limits) to make an argument about the prospects if there were a Constitutional limit on Congress’ part to authorize borrowing.