Seems I found my answer
in the archives -- it's okay to
add fuel as pods, just not remove any. The errata under consideration back in 2008 just never seems to have been actually incorporated anywhere, and I'll point that out in the relevant thread on the Errata board in a moment.
(Side note: this does make it technically feasible to create OmniFighters whose base chassis includes no "fixed" fuel at all. Not necessarily a
good idea in actual practice, human forgetfulness being what it is, but doable in principle.)