| It's just so frustrating that I have to start over every time I fall.
This achievement is rather difficult and is considered quite hard. Due to its hard difficulty, the power cell reward for this achievement is higher than most achievements. Infinite Mode level achievements are usually not affected by this and they still keep their 25-75 power cell rewards if not affected.
Straight to the End is an achievement in Run 3.
The Skater is one of the best choices because of his jumps. He can jump far enough to land on the rings of normal tiles. If he lands on a crumbling tile platform quickly do a small jump to land on the next ring or hold jump to do a far jump to a farther ring if the ring is too close. But don't get too cocky or you will jump over the ring and fall into the void.
If you want to totally cheat this achievement, use the Child and use his light weight and strange hitbox to jump of the edges of walls without changing gravity. The achievement never says you can't press left and right, does it?
The Pastafarian can use her bridge to extend jump length. First strengthen the bridge with a small jump. This is deliberate. Since you cannot change gravity for the achievement, you have to stay on the same side to strengthen the bridge. What may happen is that the bridge may disappear right before you hit it on the landing. So, to reduce the chances of this happening, perform a small jump to reduce airtime. Only do this when you are jumping from the bridge, to the bridge. Keep doing that and you should get to the end of the level without a problem.
The Bunny is also a viable character for this achievement, this is because of its ability to fluctuate in jump length.
Although he is not suggested, you could also use the Duplicator, who can jump off his duplicates to perform long jumps and has a chance of surviving when he falls off the tunnel. The width of the platform gives enough room for the duplicates to not touch the walls, so there is little risk of changing gravity.