Sharing my recent experience in case it helps.
For the old Flex v2, I found small parts worked just fine with tiny supports. For example I printed this tire using 0.4mm supports plus two 0.85mm ones where initial contact is made with the first layer of the model, and it came out perfect:
But larger parts are more challenging. This remote control sleeve failed (several times in a variety of orientations) even with a mix of 1.5mm and 2mm supports throughout:
A big issue in my case was the height of the part. The further you get from the build platform, the less rigid your support “substructure” becomes (I’m talking about both the Preform-generated support lattice, and even to some degree the earlier portions of your part upon which the next layer is cured). You get more layer shifting and localized defects. So in this case the suggestion was to reduce the angle of the part, so that the print wouldn’t be so tall (keeping everything tighter toward the platform).
That’s just a small cross-section from my limited experience with an older flavor of Flex.
The newer 80A has substantial improvements, not the least of which was to double the tear strength. You can compare properties in the chart here and also find more specific recommendations on feature size, angles etc.
I haven’t had a chance yet to try the sleeve with the newer formula, and am hopeful it will let me reduce the touchpoint size (along with some great suggestions on orientation improvements from a Formling, such as aligning the part’s major axis roughly along the mixer/peel direction, with the tallest part toward the mixer side so it “pushes” against the peel forces rather than “pulling” with the LPU).
But I imagine the general principle holds that if your part is big and tall, you need to be cautious about reducing touchpoints (and may have to adjust upward). The Preform defaults are a good place to start (although others may have more specific advice based on the dimensions you gave). If your part is small, you can probably get more aggressive and reduce somewhat from the defaults.
Good luck, and would love to see photos of how your overmold comes out (if it’s shareable)!