Welding Tips and Tricks

Hi all.. .new here, kinda new at this, here is my question and hope a seasoned (pipe welder?) response helps me do it right early on.... I have a need to weld a series of 55 gallon drums together and they are capped (solid on one end and with a funnel/cone at the other..) so I cannot get to the inside. They need to retain liquid without leaking (they will hold Diesel) So picture two drums stacked (there is one of the welds.. all the way around), then on the top is a (large) funnel/cone (there is the other weld). I gotta do about 8 of these.
So... how do I do this most effectively... MIG ? TIG ? Material is a typical 55 gal. steel drum. I assume this is pretty straight forward, but it (they) is a "long weld", I cannot get inside (for both welds... so lets assume I can't get to either,) and it needs to not leak.
On the plus side.... they are free-standing during this process so there is full exterior access.
Sorry to be verbose... I know this is second nature to most all of you... thanks in advance for guidance / suggestions.

Myself, I would say screw all cleaning and preperation and use fluxcore. this will clean all paint and chemical residue while giving you a very productive weld time.

However, if I were worried about my skill level, I would clean all of the joints very well, and put a slight bevel in each weld joint with a grinder for good penetration. Then I would go with(pipe welder style) a 6010 or 6011 root and follow with a 7018 or 7014 stickrod for a cap.
much more time consuming, but the quality of the welds is almost a given.

I'll bet you could pull it off with fluxcore though, becuase a drum just holding the liqiud(in an unpressurerized enviornment) shouldnt be to much of a problem.

-Rick

thickness of 55 gallon drums might be 16 gauge at best. would be hard to stick weld, no? - maybe the flux core would be better