Certainly the C172s I used to fly had only 30 degrees of flap, but had a warning (not an outright prohibition) to avoid slipping with any amount of flap. (It's not possible to completely avoid slipping, or else how would you land in a cross-wind?)
An interesting idea would be to compare the change in IAS when slipping to the left vs slipping to the right, and see how this fits in with the position of the pitot and static ports. I don't know what would happen, I've never tried it, but please do, and let us know!
FFF
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