I'm wondering
if a short vertical with long elevated radials would result
in an "off-center-fed" vertical.

Not the way I see it, just as long as all the radials are
equal length. The reason I don't see it, is the radiation of the
radials should pretty much cancel if all are equal. Not
quite the same as the single radial in that situation.
If you had one radial, maybe so...
MK