You seem to not be familar with sacu presets so i wanted to explain it as much as i can, and yea my english is not perfect.
People do like that you can double click all RAS presets and Rambos don't get selected and vice versa.
Fixing this separation and inconsistency would be interesting,
But as i understand that would require to create new units for every possible combination of upgrades and whenever unit gets upgraded you would need to chage it to a new unit and transfer all veteranicy and HP and whatever else to a new unit.
So for example you could take rambo and remove upgrades and upgrade RAS and it would become a completely different unit - then all similarly upgraded SACUs will get selected, because they actually will be a same unit.
One possible downside i see is what to do if rambo got to 99% of his veteranicy... it could remove one of his upgrades and get a veteranicy level? what happens if after that it gets an upgraide again? will it get demoted?
(different presets have different unit cost, so upgrades if upgades gonna change unit cost they gonna affect veteranicy and currently veteranicy is base on unit costs e.g. most of the time to get to level 1 unit need to kill 2x of its mass cost)