I'd say go through everything else first and be ruthless - ask yourself if you love that thing or need it more than your studio pieces, and if the answer is no, it goes to make sure you have room for more studio things. Then you can evaluate your studio stuff in light of what you have left.

Storage units, IMO, should only be used if you have a specific, scheduled end date for needing to leave things there. Staying in a hotel or with a friend for a month between apartments? Moving for six months but planning to return? Then it's worth considering. Just don't have space but hope you will someday? No, that's dangerous territory.

As for your art books, could you go through and evaluate which you love or reference all of and which you keep for specific pieces? Sixteen boxes is enough that I suspect you will find there are at least a few you could scan the useful/beautiful pictures from and declutter.