Hand sewing into silnylon – hooped bivy with Delrin

I would strongly recommend that you take the bivy to a tailor or seamstress, rather than hand-sewing.

The reasons are:
1. Machine sewing tends to be stronger than hand sewing, and tends not to completely unravel if one thread gets cut in the field;
2. Inexperienced hand sewers tend not to have neat, even, and tight stiches (needed for a tie-out point that will be under a load;
3. A professional will know that each tie-out point needs a fabric reinforcement on the inside of the sewing.

The downside to doing the job badly will be that either your stitches will come undone in the field (and leave permanent holes in the silnylon); or the stiches will hold, but the bivy will tear at the point of stress.

I've decided to give up on the bivy and just deal with the moisture instead of trying to modify it.