One other thing I wanted to ask is if builds without defensive stats are viable? The original build I'd seen put no points in dodge/evasion and seemingly relied on tactical vests + mobility + quickly killing enemies in order to avoid damage, though it was several years old, is this approach still viable or would it likely lead to getting mulched later in the game?
It's very important to have some strong defensive ability for your character, but the defense options are more varied than perhaps you would think at first.
Stealth is enormously powerful. I rarely play characters with stealth because it trivializes something close to 90% of the game. OTOH, if you're having a hard time with the game, be stealthy and you'll sail on through. Stealth is an incredible defense because if they don't know you're there, they can't kill you.
Psi is enormously powerful. I really like playing psi characters but it's almost as potent as stealth and there are skill synergies that really do trivialize nearly any part of the game. Psi is an incredible defense because it can make you impossible to hit, it can stop enemies from attacking, it has so many tricks up its sleeve.
Crafting is enormously powerful. If you can craft at a high skill level, you can make better stuff than any other items you'll find in the game. The broad variety of things that you can craft means that whatever your play style may be, you can craft excellent gear to reinforce that style. Maybe you want quad-plated armor that bullets and claws bounce right off of; maybe you want a sneaky trenchcoat and a cloaking device so nobody can find you; maybe you want devastating traps and powerful grenades. Whatever you like to do in the game, crafting lets you do it better.
Dodge/Evasion is a good defense. They're not enormously powerful but they're a passive defense unlike psi and stack with any other defenses you have, unlike stealth.
Line of sight and AI manipulation are good defenses. They're situational but they're almost perfect defense when applicable. However, use of these does require that you already have some good knowledge about the game and how it works.
There may be others; it's early and the coffee hasn't really kicked in yet. But my point is, you do need some defensive ability because UnderRail is a dangerous place. But there are a lot of ways to get enough defense to make it through the game on any difficulty.