Looks to me that you've covered all the bases. I've hand-pollinated two dozen Incense blossoms this year, using pollen from two different incarnata, and thus far have had none take. The parent plant of my Incense has produced fruit after insects pollinated it from wild incarnata, so I'll keep at it.

Some of the flowers with the upright styles may be male-only flowers and not able to set fruit. Incarnata tends to do this after many fruit have set, and Incense seems to do this with some flowers as well. However, some of the styles will go from down to up after pollination.

Speaking of stolen pollen, I noticed that within one or two hours after opening, very little pollen will be left on the incarnata flowers. When I bag them (cotton draw string bags) the day or morning before they bloom, there will be lots of pollen present when I get home. My Incense keeps setting many fruit, but all fall off after 3-4 days so far.

Wondering if temperatures play a role in how long the pollen stays fertile,or fresher pollen when first opens will set fruit more readily!
Another question,I have several maypop vines,some with darker flowers and larger flowers while others much smaller and lighter flowers in color.Which might be better pollinaters?
Another question,has anyone tried the tomato or cucmber bloosom set spray on the flowers?