More or less that's it.. there are hardpoints to change, and those string files to add. People apparently get cranky if there are no string files.
The one change to my tutorial though.. don't name the files something like *_BS etc... the _ in there isn't supposed to be there. So it'd be like Ubership would have UbershipBS.BMP, UbershipVL.bmp, UbershipTI.bmp, then for each texture there needs to be a D texture. So tophull.bmp and tophull_i.bmp from SFC 2 would also have tophullD.bmp and tophull_iD.bmp added to them.. with the one that's for illumination just being the lights from the damage.
So if you had a ship like this in SFC 1:
Ubership.mod
Ubership.pcx <-note
Ubership_brk.mod
It'd turn into this for SFC 2:
Ubership.mod
Ubership.bmp <-note
Ubership_brk.mod
Ubership_i.bmp <-new
And this for SFC 3:
Ubership.mod
Ubership.bmp
Ubership_brk.mod
Ubership_i.bmp
UbershipD.bmp <-new - made by you
Ubership_iD.bmp <-new- made by you
Ubership.gf <-new- made by Glowtools and Hardpoint Editing Utility
Ubership.x <-new- made by Recacher
Ubership_brk.x <-new- made by Recacher
Ubership.txt <-new- made by you - contains ship description w/class
Ubership R.txt <-new- made by you - contains ship description w/o class
Ubership DefaultCore.txt <-new- made by you - contains ship stats
Ubership DefaultLoadout.txt <-new- made by you - contains ship weapons (I think)
All with the same basic original files.