When I Push jigs/cranks I'm using 2oz for cranks & 1oz for jigs ...1.5mph - 1.8mph for cranks & ~1mph for jigs.

I "assume" that for every 5ft of line out below the surface that my baits will be running 3ft deep. I fine tune the depth by multiplying the length of line out below the surface by 0.6 (20ft line out = 12ft bait depth) I'm pretty sure my lines have never been at a 45deg angle at those speeds/weights, but it's been close enough with those rough estimates.

Remember .... the fish are not going to be schooled in a flat pancake shaped grouping. They're usually schooled in a loose oval shaped group, covering several feet of depth from the shallowest fish to the deepest fish, so being "exact" with all the bait depths isn't a major factor. IMHO, anyway. I always just tried to have my baits cover a 5' depth range spread & keep the baits slightly above the school or running thru it.