I think your IBUs are mid range for the style. You could go as low as 19 as high as 28. New Belgium Brewing Co - Long Table is a bitter, they call Fall, version of Saison/Farmhouse Ale and I would say it is about 30-35. Not 100% on that, just guestimating.
I like Rye or Crystal Wheat in my Saison. I think it fits well in the summer feel of a fruity Saison, and a nice bodied smooth drinkable finished product. As well, (I feel like I have been saying this a lot lately), think about some Special B Malt. @ ~3-3.5% It will give a raisin, rum-raisin, flavor to your beer that can help balance the spice from the yeast and boost the malty sweet aroma, and bready mouth feel. Above 4% Special B will give you caramel/toffee sweetness without toasty impressions. Which you are already getting malty flavors from your Munich, I think you could boost the body with Special B.
For a Dark Color I think that goes in the “Specialty Ale” or “Holiday ale” that you’re are close to in style. I would think about how you feel about using Dark Candi Syrup instead of Carafa Special III. Plus can’t hurt to boost ABV and darken your beer for the same $. I know that is what I need around the holidays, MORE ABV! ;D
I would +1 the waiting to see what spicy clove flavor your yeast can produce, You could always add the mustard seed to the bottling bucket just boil up with, or separate to, your carbonation. Also these yeasts can have a bubblegum flavor (And mouthfeel) too at high temps.
WLP568 can tolerate fermentation temps of 70-80F which when you get above 74 with this yeast. I am sure the spicey-clove will really get out of control if fermented at 80F.
WLP565 is another story, you need to ferment at 68-75F and you will get plenty of spice out of that if done at 73F. But I am cheap and don’t like to buy multiple vials of yeast for one batch of beer, and this one needs another pick me up, or oxygen (which I am not ready to equip) So I have, and probably will, stay away from that variety. Although I think it could produce better tasting beers.
Often these beers are corked and stored for MONTHS! And the darker the beer, the better it would probably due with capped/waxed and put down in the back of the basement until next year.