I dont know how much this will help , but Millets do fibre glass pole repair kits . Each kit gives you enough sections to make a fair length of pole (for under a £10) . You could use these to shape the tarp and just dangle it over the top of your hammock . If you made a bender style hoop running diagonly accross your tarp you could always extend the poles and push them into the ground .
Pumbaa
Pumbaa