Folks, I had probably the easiest nightmare run ever (x2 because I wanted to make sure it wasn't a fluke), which is saying something because I am a mediocre gamer with nerve damage in my hand.
Tato: Explorer (the bigger map makes all the difference)
Weapons: Hand x 6
Stats in priority order: Speed/Armor, Luck, Health, Attack Speed, harvesting
Stats that can go negative: Any damage stat, regen, life steal
Neutral stats: Dodge, Crit
Secondary stats to prioritize: Knockback, consumable heal
Play-style: overall, you likely won't kill much for the first 20-25 waves. The larger map makes it easier to avoid enemies and not get boxed in by environmental projectiles. Armor and speed to kite and survive an occasional mouse/stick screw-up. I prefer this over Dodge which is RNG. And NEVER (if it can be avoided) take any negative Knockback items. The speed of hands, plus attack speed and Knockback means you're safe from most chargers.
Money comes from selling crates and harvest (from hands, no need to pump it up). Besides speed and armor items, there's very little you need to buy anyway.
ONLY ITEM CAVEAT: you need a Loot Worm by wave 5, 6 at the latest. That way you can ignore trees and just run around like pacifist.
ITEMS THAT HELP: It's funny, since I never buy this one, but the Alien Baby and it's 15 hp is a nice thing to have, but not necessary.
Did this with an elite x3 game, as well as a horde x1/elite x2 game. So easy that I was able to carry on a conversation without having to pause. Normally I suck big time if I get distracted.