My little code research comes to this:

Metal Trunk Barrier requires 4 welding, weights 10, 6 metal sheets
Net Trunk Barrier requires 2 tailoring, weights 2, rubberstrips, screw and needle

durability and damage reduction (none) is identicaly treated in code (very fragile)

seems like net is better because of lower weight

if you care for your items in trunk avoid ANY damage to the back, however i did not test <15mph pushing

please do not trust my inferior code intepretation skills and check them for yourself