I'm starting off as a Kajiit. I'm beating the crap out of Hadvar as he watches the bear near the end of the tutorial, using an iron dagger to get lots and lots of sneak skill. My goal is to get enough sneak skill that I can sneak past the Flamer in Alftand and Blackreach without the need for any perks (I want to be able to SAVE without any skill perks being spent, so I can reload that save whenever I want to try a different style, without having to go through the leveling process), so that I can use the Oghma Infinium glitch to reach level 81.

But it's sooooo tedious. I've got my sneak up to level 75. Is that enough to sneak past the falmer?

Use an invisibility potion or spell and make sure you are either barefooted or use the muffle spell or some boots with the muffle enchant on them. Even if they can't see you they can still hear you if you have on noisy footwear. 75 is pretty high but with no perks it's hard to tell without actually giving it a try.

How can you break you game so it is almost unplayable? Sounds like you’ve figured it out. Have fun.

With a Sneak of 75 and a muffle spell, you will be all but invisible. Just being barefoot will not help...much. The detection factor that is governed by weight is taken from "total" weight. This includes clothing and even jewelry. This can be easily tested by getting naked and sneaking up on a guard. This is more prominent at low sneak skill levels that after...say 50.

At a skill level of 20 you can see that you can get closer to the guard if you are completely naked as opposed to even wearing a necklace and ring.