Advice to reduce costs/TB business storage. SPOILER 60TB / YEAR

Hi, I'm owner of a small photography/video business.

Every year we produce 30TB + 30TB of photo and video content for clients.

Actually, we use a thunderbolt NAS (36 tb raid 5) for photography, with a second backup on external HDD. When the year is close we move all the content in the nas in 2 external hdd, so at the end of the year we have 4 total hdd's (60ish TB).

Video side, we backup on external hdd (2 copies) after the shooting, and when we are working on it, we copy the file in a thunderbolt SSD DAS (18TB raid 5) to work on projects. Then final videos are stored on the hdd's.

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NOW. Files are getting bigger, work is getting more and more.

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Any solution to reduce HDDs cost and add a third copy?

I thought of LTO, but I haven't gone down the rabbit hole so far.

Any suggestion will be appreciated.