Can I survive using only light armor? I don't like being heavier armors because of the loss of agility and how much they weigh. However, I'm currently at Level 14 and get my butt handed to me by Deathclaws, Lakelurks, etc. Is it just a matter of leveling up a bit more?

I have mark II combat armor, with toughness x2, and the +4 DT implant. My DT is at about 35. I still get rocked hard by lakelurks and deathclaws. I believe deathclaw attacks ignore DT. The best way to deal with them, that I've found, is to kill them before they hit you.

You can certainly survive with just light armour, but you need to try not getting hit too much, which means stealth (and stealth crits) is your best weapon.

Also going for the legs/wings instead of the head can sometimes pay of better than going for the head out of stealth. If you aren't going to kill it, better to cripple it than just make it angry

Oh, and don't forget mines.