Well 1fast340 Even being a body man for 40 years I learn new things all the time.
Your plan sounds good, If I were you I would not over weld on the frame because it is made from a higher strength steel and over heating it will make it week. And you should use a weld through primer on all your overlaps so it won't rust later on it comes in a spray can and not real expensive.
Would love to come to Sweden I bet it's nice there, and your English is just fine.