I'm new to welding and was about to buy a cheap $100 flux core welder on Amazon to weld areas on my fj40 that I cut out due to rust. After alittle research I found out that if painted over flux core the paint would bleed after a couple months. I told that to my friend that is going to teach me to weld and he said just grind the welds down put bondo over it, prime and paint. Is that the correct way of doing it, If not what is? Spots to be welded would be rear sill, driver passenger floor boards and areas where the roll bar bolts to. Just want to make sure because I don't want to redo a mess up months down the road.