From my own contraption experience, the need for single vs dual depends on the contraption orientation. You can have a floppy or a twirler.
Floppy
Twirler
I found that the floppy's tilted up angle could be left alone so all you need do is flop it, but that the twirler needs to be tilted up more when facing SE or SW and lowered for facing S mid-day.
If the twirler is not tilted up and down as required like that, then it gets fewer AH/day than the floppy single axle.
The hard part making a floppy is to get the bottom end up high enough off the ground so it can flop, which means the top end has to be quite high so the panel is tilted.
The twirler if mounted at ground level on grass, needs a loose string across the top so birds (robins mostly) don't perch there and poop down the panels.
Both contraptions only need to be moved three times a day: at dusk to SE, late morning to S, and mid- afternoon to SW (when noon is 1pm) Paying for an automatic system would only be necessary IMO if you were away from your rig most of the day.
I found it was no trouble to move the contraption if there, and if going to be away, then just moved it ahead of time or left it there until return depending on timing.
