custom fender struts

Do I use bondo to fill a custom chopper gas tank weld?
I am building a chopper, and I’m doing some welding and stuff to the tank/fenders. Do I use bondo to fill/smooth everything out? Do I put it over the whole tank/fenders, or just the weld? Do I have to worry about it cracking later? Do I do it before or after the primer goes on? I want to weld in my struts for the rear fender, so it’s a strutless, or kind of. Then make it look like they are not in it.
Any tips?
Assuming you have ground down the welds, you can use a little filler as a cover…do it before you primer, sand it smooth, make sure it’s clean and fully cured, then primer. Hope this helped.
DOC’S BICYCLE CHOPPER – DEADLY SPIKED FENDER STRUTS