Industrial Evolution and this mod are essential for every playthrough! Thank you!
Would it be possible to base the "cramped infrastructure" modifier on planet size? And by that I mean the size of the planet on the map, not the colony size. The "Terraforming and Station Construction" mod (also a must), does something like that with not allowing stations to be built around small planets, so a planet size seems to be at least somewhere in the game (I don't know why it isn't used anywhere in the base game).
Of course colony size itself could also influence the cramped infrastructure limit. Like going from 5 to 8 to 11 to 14 to 17 to 20 "slots" (on respective colony sizes 3 to

before the cramped infrastructure kicks in.
Combine the two:
Every planet has a base of 5 at colony size 3 and depending on planet size "slots" are added every time the colony grows.
A small planet adds one per colony size (5 base + 1 x 3 = 8 slots a colony size 6)
A medium planet adds two per colony size (5 base + 2 x 3 = 11 @ 6)
A large planet adds three per colony size (5 base + 3 x 3 = 14 @ 6)
Not only would that give planet size some use, but it would also make cryosleepers (together with the "Ashes of the Domain" mod) more valuable, as on a large planet grown to colony size 8 "cramped infrastructure" would only kick in after 20 buildings.
The numbers can of course be tweaked. And I don't know how planet sizes are represented in the game (e.g. if there are fixed sizes or they are continous), so maybe we can even have some in-betweens (like 2.5 slots per colony size, but rounded down).
I hope you consider the idea!