The dog in the tank is funny. Not a great idea, but funny.
If you want to "re-seal" the tank, you will need to remove the seams as well....that is a major pain in the aft end as you often will need to remove the rim and base trim, usually resulting in it breaking....thats why I would have a shop do a major.
If your just re-doing the corners for aestetics, then yeah, stip of the old, dont disturb the seams(cut to deep) and re-apply the silicone. Tape makes a clean line and so does a straight edge and a little skill with an x-acto.