First of all, you should check if it's allright to mix enamels and acrylics.
Anyway, you may wish to consider using a different type of masking material, such as parafilm/etc., or just cutting along the edge of the tape before you remove the mask. Either way, I think you'll have to repaint it. It might help to burnish, or press down, the edge of the mask real well.
Also, I don't think it's a good idea to sand a final coat.
It might be handy to know what your model is, and the specifics.