I have done this a couple of different ways. The easiest is to manufacture something to insert into the pole end. To do this, I would purchase some rod aluminum (tubular would work), or even dense plastic rod (solid), from your local hardware store. Or, use an old aluminum tent stake. This would be sized to fit into the end of the tent pole. Cut it to 1"-2" long and drill a small hole in the top end to run your tent line through. Permanently tie your tarp ridge line to this close to the tarp. Set up by erecting your poles and inserting the aluminum rod into the pole end. You will want to buff all the edges so neither the line nor your tarp get shredded.