Power supply sources and droop

One of the many reasons I cannot finally make progress on the power supply is I keep falling short of the current demand. Sources keep having internal loss issues, and we're only talking about a few tenths of an ohm here, but it adds up quick! real quick!
I bought some 12V high current smps' to alleviate this, but they were operating too close to their limit, so I opted to go with the lower voltage 5V units, and it would seem they have less losses to contend with, which is the direction I need to go in.
Now the big issue is, can I fit 6, 7 or perhaps 8 of these damn things in a box?
The weight will be down by 50%, we will hit our power goal, but will it all fit?
2x 12V 40A power supply droop to 18.5V, 37A, 24% droop at 71% capacity
5x 5V 50A power supply droop to 23.5V, 47A 8% droop at 88% capacity
So we have a big difference here in performance, and there are more links in the 5V setup to contend with, so the differences are pretty staggering.