An 80ft dipole with ladder line won't buy you much that you don't already have. You might consider putting a coax switch out at the pole and running a second vertical wire off the pole and feeding that through a remote antenna tuner. I use that setup with a MFJ 929. You can use the coax to feed voltage out to the antenna and you can set it up so when the voltage is on the vertical and tuner is operative and when the voltage is off you are connected to the dipoles
AD5X has info on running voltage down the coax and a 2 position remote antenna switch at his website. If you want to run power use a 994 or a 998 tuner
Here is a shot of how I did the vertical
http://w9oy-sdr.blogspot.com/2009/09/43ft-vert.html 73 W9OY
