Wouldn't you have fitment issues if you tried the "deep sump" approach, assuming it is even feasible with the casings on these transmissions not really having a pan? If, and I mean IF, you could have a custom piece made by cutting into part of the casing, possibly, then there would be clearance issues with the exhaust, belly pan, ...
There has been a tiny amount of attempts made to improve the trans, specifically, a higher stall converter, but that failed to yield any performance improvement.
I think if you could figure out where the flow restrictions are inside the transmission, where the weak solenoids are, that kind of thing, you could actually improve upon Ford's design. Not a project taken on casually, or for someone who does not have deep pockets.