I think we need to indicate all those troops that can be transported (to distinguish from those that may not be transported) as well as whether they are bulky or not.
So let's consider how this would work with the Marines. If I have understood you correctly we need additional definitions to cover vehicles and infantry, and the transports that carry them. So we would get something like the following
- Tactical marine, Inf, TI(1) = transportable infantry (1) slot
- Assault marine, Inf, TI(1), except Drop Pods
- Terminators, Inf, TI(2), except Drop Pods
- Dreadnought, AV, TI(2)
- Land Speeders -
- Predator Anahilator TV(1),
- Land Raider TV(1.5),
- Drop Pods, Transport a formation of TI units
- ThunderHawk, Transport capacity TI(6)
- Landing Craft, Transport Capacity TI12, TV(6)
If I have understood the principle correctly, E&C is correct that this will require rewriting virtually every entry of each list, a vast undertaking. It will have an impact on the layout on the quick reference sheets, and even this approach needs further refinement to cater for Spaceships, which do not have the same space constraints as ground vehicles, and can also carry vehicles capable of planetfalling.
Colour me 'unconvinced' on this whole exercise, on the grounds that the existing approach may be a tad long-winded but it does work, while this alternative is arguably at least as long-winded and clunky IMHO.