Could add the filter to the website that will effect what data is sent in game, that way you kill 2 birds with one stone. Just allow people to save groups of armor/weapons. Have checkboxes for each build made(and the standard all option from which the builds have to be orignally made), and that is what is sent to the server. If you have as many items as you say, unlocking and relocking all the items you don't want to see would take a major overhaul each build, and probably considerable time. If you just pick and save from the all items menu, it would be much quicker. Undoing one would be as simple as clicking delete or de-selecting it.
Also to add this you can just put a checkbox on each piece of gear in the main chest, and a save/add button up top. Save would ask you for whatever you wish to name the set. Add would obviously add the items to current builds. Then put the check boxes for which gear will be shown right next to where you save the default loadout of the character.
