It would be easy to just overlap the joints but no matter how much grinding you do, it will still look like butt. Sorry to be blunt but you would forever be explaining why it was done so poorly. The only proper way is to fit pieces between the gap, butt welding. It's not easy but nothing worthwhile ever is it seems. Take your time, try to get as tight a fit as you can - excessive heat is your enemy - use a lot of very small tacks, moving around a lot and let it cool down frequently. If you start to get warpage, work it out with a hammer and dolly as you go - don't wait 'till it's all welded to iron it out, you'll have a mess on your hands. Once you have the patch strip initially tacked in place, sand the bumps off the tacks so you can hammer it smooth better - then do another round of tacks, sand again, repeat, repeat. If there's one big lesson to be learned it is don't rush it.
Show us pics of the build as you get going on it.[P
