[Towertalk] 40 meter boom, 80 meter dipole?

[Paul Young]

I have a three element 40 meter beam.  I'm thinking about
matching the boom as an 80 meter short dipole.

The boom length is 48'.  The driven element is insulated but
the parasitic elements are connected to the boom.  They are
full size and provide plenty of end loading.  It has a T-bar
truss which is not insulated but I don't think I would want
to use it to feed the antenna.

The problem, of course, is feeding it.  Tilting the antenna
is difficult, but I figure I can tip it once and install
some sort of omega rod.  Then I can tune it from the mast.
The bandwidth may be narrow enough that I'll need to put up
a relay to switch it to phone.

Has anyone tried this?  What sort of omega rod will I need?
Any caveats?

                           Paul, K1XM