Fully Loaded Trophy... glitch? Help please

Hey everyone I hope somebody can help. My boyfriend and I are avid fans of Borderlands, we play splitscreen local co-op, him on our main PSN account and me on our 2nd, created purely for this game! We have rescued all the claptraps and have 42 inventory slots, alas, neither of us have the trophy

Our PS3 recently died and we lost our 2nd PSN account, so I've lost my character. We our looking for a solution by playing with his level 46 Roland and my now level 5 Lilith on our new 2nd account (so i'm the host) hoping in my game he can find a claptrap, get the SDU then re-load the game on our main account and open the SDU and hopefully bling... any comments or suggestions if this is the right thing to be trying? Or our we better off just starting a whole new game (we did 2 playthroughs on Xbox and 2 on PS3 already) on our main account and hoping we get the trophy then?

(we only have fully loaded, Ding! level 50 and kills with Hunter, Berserker and Siren's action skill left for the platinum!)

thanks in advance