Change spell slots on items for spontaneous casters (Sorc / Bards) to Spell charges (like the wizard generalist re-generate spell slot), so if you had 3 bonus 1 slots and 2 bonus 2 on items, on rest you would gain those charges and use a play tool on yourself when you want to restore or add that many to each slot. This would be a good way to get around things like polymorph losing slots and mean that sorcerers/bards much like prepared classes. I suppose you could do it with all spellslots, but might be a bit strong being able to change multiple slots as you go taking away from the whole preparation side of things.
I really wish there was some workarround for the current issues... I rarely get to use Alter Self (which I still keep bc it feels too thematic!) because of spellslots issues...
I think the idea of restoring and simply keeping them would be useful. Another option would simply finding some way so that nwn counts the item slots as used "First", so you don't lose it when re-equipping...?
I honestly dunno what would be workable. I just reeeaaally feel like this would be neat!