Topband: AM broadcast estate of K9FD/KH6

[F3WT]

Boy, It reminds me the Island of Sein, one of  most west located  
Brittany-island of France near Brest which has still its light-house
and two masts rusting waiting for Hams and  IOTAs  contests  
operations...

Now back to your questions:
Your 2 masts  are probably over 80M high, e.g. a bit over halfwave  
high for 160M if they are  quaterwave high on 870 kHz...  whatever,  
but great low angle take off radiation!
On top-bands, a shunt (unipole) feed  at half mast or lower or higher  
even from top should do it . Run a wire from midheight tap or even   
top of tower sloping directly to your
hardwire-300ft  // feed-line . One // wire  to slope, other to common  
radials groundpoint.
Use al coupler at your shack to match your TX to your  said // hard  
feed line.
Should amaze!

Pierre.