Treestand safety harnesses should be properly hung so that you can reach your ladder, rungs, or tree stand even after a fall.
By design, these harnesses:
1) Cannot take a long fall. Really even a short fall. Your harness should be set up so your HEAD cannot go below the platform of your stand.
2) Should NEVER be adapted or altered to put them in a position where they would take a long drop if you did ever fall.
So really, the only guys that NEED an escape ladder are climbing stand hunters, where your platform falling away might be why you fell.
A 550cord LADDER would be very foolish. You might be able to get away with using 550 and a belaying devise, but no way a ladder works safely. Make a loop out of 550 at the end of a 4ft lead. Stick your hunting boot in the loop, then hold the lead in your hand straight up, as it would be as you climb out of a stand. Try to remove your foot from that "rung" as you would climbing down a rope ladder. Call me next winter when you finally get your foot out of the loop.
Then do a pull up hanging by a loop of 550. Your hands will F'ing hate you.
I have a Live Wire descender, if I fall, at least I know I'm not going to hit the ground at 20mph.
One of the most important things a hunter can use, however, is to add a "step rope" to their harness anchor. Snapped to the same anchor, and just long enough to reach about your knee when held above your head (as if you had fallen out of your stand) with a loop at the end, then tucked in the front of your harness. When/if you fall, you can un-tuck the end, pull your leg up and put your foot into the loop. You can then step up on the "step rope" to either take pressure off of your legs in the harness, or help you get back into your stand.