I gardened in Zone 6 for many years and can give a thumbs up to the tall verbena and cosmos. The verbena is a stiff, upright plant and lends support to any cosmos inclined to flop.

In my full sun midwest garden I found that in the heat of July/August, the cleome looked exhausted by late afternoon. The next morning a fresh new cleome flower would appear only to repeat the cycle and look tired in the late afternoon sun.

I have no experience with 4 o'clocks but understand they have a wonderful fragrance (and self-seed prolifically).

If your plants are closely spaced. you'll want to be attentive to the MG, at least initially, so that they twine up the stringers on your wall and not around your other nearby plants.

Good luck with your planting. It's always exciting to try new plants and/or combinations. - June

Is the tall Verbena that you mentioned Verbena bonariensis?

Yes I will be using the Verbena Bonariensis.