No interstage fairings in SPH?

[KerikBalm]

I noticed something strange/frustrating:

In the VAB, I can make an interstage fairing, but I cannot do such a thing in the SPH.

In the VAB, I can end the fairing by having it close against another part.

I tried this in the SPH... but it won't let me, and I have to extend the fairing around everything... which is not what I want to do.

I was making this beast:

And I wanted it to end at a 2.5m docking port ->service bay (with probe core, 1.25m reaction wheel, batteries, solar panels, and 2 of our beloved round 8 tanks) -> tricoupler + triple LV-Ns

My idea was to shut off the KR-2L's and rely only on the LV-Ns for the final parts of orbital insertion (yes, I'm aware of potential heating issues).

I would then undock the nuclear module and jettison the fairing, undock the payload, and then use the onboard fuel in the nuclear module to redock it.

This would also have the nifty and useful effect of shifting my center of mass forward, since often empty spaceplanes are tail-heavy.

-But alas.. I can't have the fairing seal around the front of the nuclear module, and it just won't work.

Surely this is a bug, no?

Or am I just doing something wrong with building fairings?

Edited April 29, 2015 by KerikBalm