Richard, I wouldn't worry too much about the vee being more than 120 degrees... the dipole I'm running is more like 45 degrees - I know it's not as effective (or so the books say) as if it were more like 120 degrees, but one must use what one has. The 40 mtr dipole tunes pretty good - 1.5 or so - with out atuner on 40 mtrs. I can also tune it to a flat SWR on most other bands - not 80mtr, but tunes nicely on 160 mtrs with the tuner. Now the the effectiveness leaves a LOT to be desired. The differece between the insulated backstay tuned useing the SCG autotuner and the 40 mtrs dipole is a LOT on 20 mtrs.
On 40 mtrs, the 40 mtr dipole wins by mabye 1 S unit(this is guessing as I'm just looking at the meter on the ICOM 706). Some times the received signal is better with the dipole but the station on the other end heard the backstay better.
On 20 mtrs, the the backstay wins easy 1-2 S units.
On 160 mtrs, the backstay wins by 2-3 S units (again just guessing).
I've know some folks to just load up the rigging with a tuner and talk pretty good with that.
BTW, for the backstay I've got a fairly good ground system using one of the biggest grounding plates I could find (18"X6") also a copper grounding strap, and a #8 wire about 70' as a counter poise...
MFJ suggests using the center part of the SO-239 for a single long wire antenna. Also, they suggest doing the same if you are wishing to use a dipole on less than it's resonnat freq and are using a ladder line. MFJ says connect both sides of the ladder line together and connect to the center portion of the SO-239 in this case also and feeding as a long wire with the dipole acting like the cap hat. My question was directed towards this idea.
I've been planning to disconnect the SGC auto-tuner from the backstay and feed the backstay with a single wire from the MFJ tuner, I just didn't really want the active part of the antenna inside the boat. Not that efficent, but just for testing some day it would be ok I guess from a safety aspect - IF I don't try to hold the wire while tuning up the amp:)