To get an aerial back up for 160/80mb, I have now installed an 18m Spiderbeam pole, with a 20m wire as an 80m 1/4 radiator wound around it (approx 5 turns per section) and another 20m wire with 3 x 15m drooping radials at the 15m mark to resonate it on 160m. Then I've started running out the first of 36 20m ground radials. The ones around the grass where the cabin sits are buried, the rest are running along the surface and held in place with aluminium pegs fashioned from old TV antennas. So far, 27 are in place with the remaining 9 set to be in place by the end of March. Then I'll add some 40m wires (8 or more) for 160mb. I'll experiment with switching/feeding arrangements so the two wires will live happily together.
Here's the design kindly made available by SM0MDG: