I found getting a nuclear stick welder worth every bit of its 20 quid. I just hold the stick as far away from the work as possible and let the rod spray steel all over the chassis until a good thick crust covers everything. Oh and wear a hat and make sure you squint.
Best bit is getting the kids involved................ they love welding the car with dad.
Sage advice. Especially the bit about squinting, you can't be to careful.