So here's what I did (aka simplest DIY ever):
- Put a terracotta saucer in the bottom (as if by magic, I had one just the right size).
- Lined the sides of the basket with sheet moss
- Took the hanging hooks off the planter, placed the pot inside the moss and tucked moss in any gaps
It just hangs it from one of the window latches, so didn't have to take out a drill at all. So simple and I love it!
Note: Even though I put a saucer in there, I won't water the plant in situ. I'll take it down and water it in the sink, let it drain completely before rehanging. The saucer is just there as a precaution for any leftover drops.