I have fished several store-bought lines....and I have made some home-made lines as well. my two cents on trotlines....on the store bought lines larger fish seem to strip out the staging stops...I have used the brass brads to try and repair...they strip those too.
on my home-made lines...I used 1/4in nylon rope....and made my stage stops with a double knot on either end of the setting. I've never had these strip. I would also use the largest barrel swivels you can find. I use 1/0 ones. they seem to work well.
in texas state law states hooks must not be closer together than 3ft interval spacing. I would spread this out to 5 or 6ft. 3ft works.....but its a lot closer together than necessary. and if you were hook two better size fish back to back it can be problematic