IME, late blooming or pruning group 3 clems have the longest bloom season, typically starting in midsummer (July) and continuing until frost. So that would reduce the possibilities to Nubia and Princess Diana. Both more red than pink or purple but Nubia is pretty compact and Princess Di extremely floriferous. I know what my choice would be.......:-)

btw, the others listed are not very red, in addition to having a shorter bloom period. Lots of purple overtones.

As to combining Jackmanii and SAC in a container........I wouldn't recommend it. SAC is a house-eater once established. A very big vine!! I wouldn't even plant the two very close together in the ground.

I don’t know if it’s the shade of pink you’re looking for, but I really like Comptesse de Bouchaud. Here’s mine, growing through a crabapple Royalty. Both were planted last year. The tree is about 8 feet tall, and the clematis was tiny when planted. I’m impressed at how vigorous it is.

Princess Diana is a beautiful plant. A friend's grows vigorously on a trellis and is covered with blooms. I love the nodding bells. Mine's just a year or so, planted in too much shade and still made it to the top of an obelisk and flowered modestly

Gardengal, thanks for the insight. Rouge Cardinal and rosemoor are also type 3 with similar long bloom period. But you may be right about their color having purple hues.
Pink champagne is type 2, but is supposed to bloom may June, August and September (repeat bloom) so not bad. Also, it seems to be mostly pink and white and not purple from what I can see online.
I should mention that my North West balcony starts getting less and less sun in late summer with probably only a couple of hours by September end. That would probably neutralize the advantage of type III blooming till frost unless I move it indoors....
How does Nubia compare to Niobe in color? I am afraid it may be as dark red/maroon/Burgundy as Niobe. I would prefer more a mandevilla red (probably not to be found in a clematis color) or pink without purple hues...
Thank Marie, I am tempted by princess Diana for sure, for the color and the distinct bell shaped flowers.

Mazerlom, that i quite the energetic vine. It is a bit pale for my tastes I think.

Regarding the SAC gardengal, you would be surprised how the adverse conditions of a container existence in a limited sun windy balcony can make vigorous plants wimpy. My Jackmanii plug started early spring is barely a couple of feet and gave 3 blooms. I will keep them apart and see how they take off before trying to put them together.

I am going to get pink champagne and princess Diana. Not sure about SAC yet, it appears to bloom for only a couple of months which a big downside for me. I got a peony a couple of years back (yet to bloom) and truly regret the real estate its unproductive ass occupies...…..Still looking for a red clematis...