Iceberg and others have managed 2º on the T-90, but it's using creative techniques.
Some early attempts consisted of grinding down the cases of some LNBs to get them closer together.
See the archives for how that worked out.
More recently, some narrow-horned, band-stacked LNBs were instrumental in getting what I think was reported as reliable 2º spacing...
Read the threads for better info.
As for Ku and C band on the same bird/lnb/dish, that works just fine.
The frequencies are quite far apart, so there is no interference.
Otherwise, we wouldn't have dual-band satellites, and dual-band LNBs.
The problems of crowding "97Ku/99C/101Ku" would be strictly mechanical.
But if that was your goal, I wouldn't consider putting my Ku LNBs on a BUD.
Put 'em on a little dish.