Topband: Add top-loading to 43 ft vertical

[Philip Zminda]

I would like to try my hand in the 160 contest this weekend. My antenna
is a 43 ft vertical. I don't intend to use it as-is or add a base
loading coil. I have heard of adding a wire to the top to act as an
inverted-L or adding several wires to act as a top-hat. I will be using
the internal tuner in my K3 and running 100 watts. I have 60 radials,
mostly 43 ft and a few 60 footers. I don't have many options for
supports but could put a 23 ft fiberglass mast temporarily at my shed
about 100 to 120 ft from the antenna and run a sloping wire. Which might
be more effective? What wire lengths should I try? 
 
My only other option is an 80 meter doublet fed with ladder line that
put up for Field day. If I put it up it wouldn't be very high. 
 
For receiving I have a magnetic loop.
 
Any suggestions appreciated.
 
Phil N3ZP