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It's a good idea. Most long focal length scopes can't get to low-enough powers for terrestrial observations.
It's a bad idea. As the magnification goes lower, the exit pupil grows larger. So, unfortunately does the size of the secondary shadow.
Let's take a hypothetical 90mm Maksutov with a 1350mm focal length and an f/ratio of f/15. A 32 Plossl would yield an exit pupil of 2.13mm, of which the secondary shadow would occupy the central 0.64mm. That works OK if your daytime pupil is at least 1.5mm (1.5-2mm is common).
But, cut the f/ratio to f/7.5 (a 50% reducer), and suddenly the exit pupil is 4.26mm and the secondary shadow occupies the central 1.28mm of that.
If you daytime pupil is 1.5-2mm, the shadow of the secondary will occupy most of the field and you will see the shadow covering the central 75-80% of the view, which would be unacceptable for daytime viewing.
The secondary shadow problem is why nearly all spotting scopes (daytime scopes) are refractors.
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