Try using zombie tactics for situations like that. Put on Reraise, drag the mobs far away from spawn point. Kill as may as you can before you drop. Let them return to their spawn point. Reraise and recover. Put reraise on again, start the cycle over. Should get easier when you have fewer targets pounding you.
I'm not saying I'm opposed to allowing Trusts in these fights. Just trying to help.
As for Seed Crystal.... you can sub DNC (you really should if you're a melee trying to solo stuff) and stun Seed of Deference.