Unfortunately, this isn’t going to lower your risks at all. Protecting those moles with sunscreen, when sunscreen doesn’t block 100% of UV rays, does not stop them from being affected by the rays. On top of that, moles change whether or not they’ve been exposed.
As far as leaving the rest of your body unprotected, congratulations, you’ve allowed for a way larger area to be damaged at a cellular level, which potentially will cause new, malignant moles to grow.