Outdoor option

The long Christmas-New Year holiday is almost over. The Christmas tree has gone and the tinsel is back in the box in the loft - and I'm itching for some adult fun...
With the girls off school and uni we have been in fun lock-down since early December. For some reason SO is horrified by the idea that they might discover that parents do have sex; presumably they assume we did it twice for procreative purposes and then said that's the end of that.
I have been tempted to suggest some sort of shed-related encounter. We have one at the very end of the garden well away from the house (and the neighbours' houses for that matter).
But the whole woodshed discipline thing doesn't really work on this side of the Atlantic and, anyway, our shed isn't that sort of shed.
It's rather like the one in this picture. What on earth is he planning to do in there? There wouldn't even be room to swing a meaningful spank, would there?
No, our shed is dusty and damp, there are spiders and dead flies and it is about as un-erotic as it could be. No kids come Tuesday though, so the wait may be over soon...