Yes and no.
If the collision polygon dont matter. Yes. Just make the polygon 2x3.
Else. No. Not that i know.
Unless (i not gonna try it) the following works.
2 objects. 1 with collision polygon 2x3. 1 with the desired collision polygon. Hinge (got to error and try witch hinge, i dont know, probably with a constraint angle) them. See if the collisions for the second object do effect the first object in a correct way. Would be the equivalent of a pinning a face object on a helper object.