Most (not all, of course) dialog options are gated by Persuasion or Intimidation for gathering info or changing effects, or Mercantile for changing rewards. So pretty much regardless of your stats, all you need are a few dozen points in those skills and you can use gear and buffs to get you to the thresholds you want.
You're probably going to want 7 Int if you're serious about crafting, since most of the best crafting feats are gated by 7 Int; that'll help you get that Mercantile. Even with 3 Will, you only need like 30 points in Intimidation because there's a lot of +Intimidation gear in the game. Persuasion will be a little more costly for a 3Will build, because there are fewer gear options to boost your skill, more Persuasion checks (since it has no combat utility, unlike Intimidate), and a lot more medium-high threshold checks.
Fortunately, tin can AR only really requires one skill - Guns. And it doesn't require maxing Perception, and it relies on mitigation not soaking so you can run it with only moderate Constitution, and aside from 6 Agility you only need Perception, some Stregnth, and whatever Con you can spare. So you should be able to get 7 Int as well.
Depending on how you feel about using food buffs to keep your character working, you could use something like
this as a skeleton build for stats and skills. The downside is that you'd have to work up to those thresholds so you'd have a longer power curve to ride before you get to full stompy murder machine power; the upside is you'd be able to hit all the thresholds for everything and still have a lot of skill points left over for other things that you could have your character do.
Tin can AR is pretty forgiving, because it's terribly powerful. Aside from probably needing to do a few merchant runs to keep your ammo stockpile topped up, it's about as simple and un-demanding a build as UnderRail offers.
edit: fixed link