Singing both ways

Good God--and people wonder why I hesitate when I'm asked what part I sing.

Consider this. In the span of about three weeks, I've been placed as a Tenor II who should move up in a three-way split, and as a Bass I who should move down in a three-way split. As a result, I'm being asked to sing either tons of high B-flats or tons of low E-flats.

What's worse is that the tessituras (where you spend the most time, not just the extreme notes) don't overlap at all. The tenor tessitura (in the pieces I'm singing) is about G below middle C to E above; the bass pieces are more like low B flat to F sharp. It's really confusing me--particularly because my solo repertoire cuts right in between the two.