In past decades I lost some antennas and pull lines in trees. I always felt bad since they may be there for decades. For decades now I usually just use something like an easily breakable string to hoist my dipole or whatever up near a limb. If things get stuck I can just jerk on the feedline or antenna, the string will break, and little or nothing is stuck in a tree. Now cotton kite string (if it is even available now) is not easy to pull over limbs but should last for a few outings for sure. I have an extendable (Jackite ?) pole about 32 ? feet long. Often I just hook my antenna to the top or near the top of the pole, and lean the pole into a tree limb, or perhaps bungi it to a fence, or something. Also sometimes I stand on a picnic table and just place my wire on a branch perhaps 40 feet above the ground.
If you use your speaker wire antenna, and need a little more length, one option is to short the far end, but feed your rig into only one of the two wires. However since the wires are so close spaced with unknown insulation, probably there is significant loss, but your rig may be able to be loaded. I have done this in the field when I did not have enough wire. This is called linear loading. If your wire is 33 feet long, it will be resonant near 7 MHz. If you only run power up one leg, the wire will act roughly like perhaps a 50 foot piece of wire...so possibly with your ATU your 40 meter quarter wave wire might be "useable" on 80 meters.
Linear loading is usually not the best option, and even a less than perfect loading coil will usually be better. If the wires were well spaced and insulated, and the return wire did not come all the way back to the tuner, the efficiency will be better, but again a coil with clip leads, is easy, and often better. Rick KL7CW