On the troop loading screen, it shows the cargo space adjusted for amphib loading. Which is more where you need it.
In some places, the 3-day supply is included in the unit's equipment cost and other not. I will add the 3-day supply to those missing places for Amphib TF.
The main problem is that the totals can be calculated as a base, but how the ships are loaded can change that.
Eg equipment cost of 100 could be loaded as 100 on AK ship, but use 500 when loaded on a AP ship. It is not possible to exactly determine how the load will be distributed, and that mucks up the view.
Here how the original Amphib TF looks after it loads, but still a fragment left behind:
Both troop and cargo are near to max.
1. Playing around the supplied save some more, it is actually TROOP space that seems to be at a premium. Adding another AP (now TF has 3xP and 2xAK) actually enables all 7th/B to load.
2. To the initial TF (of 2xAP,2xAK) I add a AK (6400 capacity) instead of the AP. Again it fully loaded. Interestingly, the amount on used cargo capacity showing on this TF after it finished loading was 15061.
The difference can be explained by the 3-day supply.
For an Amphib, I am going to add a factor for the 3-day supply to increase its requirement. This should then increase the cargo space required on the loading troop screen. The correct cargo capacity will be used during the load, but this just highlight a possible shortage. Another way to cater for this would be to assume that you need a cargo safety factor of about 90% or more.
For Japanese amphib loading, there is a higher density/packing of troops which probably explains them fitting better.
The same original TF as a Transport TF will fully load the 7th/C (in strat mode) which is same size as the /B unit.