5 doesnt cut it anymore tbh, why not increase it to say 10

we already have Scruuge Hoarding Vault, T.O. Harvest Vault and Q-Pedd Science Station
each of those = around 2 to 3 extra storidge units of theire type, and you can put 2 of them on all your storidge planets

But people don't really put them production+storage stuff on storage worlds do they?

depends on the player
I know I have a few T.O. Harvest Vault IV (size 2, Mining: 4, Mining Storage: 5000) on my storidge planets
as it was cheaper to buy 2 of those then getting 5 Mineral Storage Tower...

and same with Q-Pedd Science Station 4.0 Research: 4, Research Storage: 5000
+ it quite easy to make the storidge planet x15 to x19 in recearch if you actualy need the recearch they give

unfortunaly the new versions can no longer be lifted, so wouldnt put Scruuge Hoarding Vault on storidge planets
unless you have the old Scruuge Hoarding Vault III (size 2, Artifact: 3, Artifact Storage: 6000) version, witch you can lift and replace as you like