How can I plant these troughs?

[PrincessPilolevuofTONGA]

I bought some metal hanging trough things. They've no drainage holes. I suppose ideally I'd put plants in pots in the troughs, but I don't have enough of the right size.

Can I put a layer of gravel in the bottom and plant directly into them? It should I punch holes in the bottom?

you would definitely need drainage holes if you plant directly into them.

how hot will they get? Best to pick plants that will enjoy the heat. Ivy-leaf geraniums, verbena...