Nice looking design! You could try some Soss hinges, which come in barrel or slot versions. You'll only get 90 degrees of an opening and will need to be careful mounting them, but I've had a student use them successfully on a similar project. I recommend using them on the leg tops rather than the rails, as those are the outermost points of the base.
I think I'd look into a piano hinge. Can't really tell how much space you have, but I've used piano hinges many times on lift tops. That said, I recently used these hinges from Rockler on a toy box. In the future, I'll design my lifting tops around this hinge. I have a table in My Photos using a piano hinge. Lid-Stay Torsion Hinge
Another thought is to hinge an apron instead, giving you access from a side. If the top and bottom are rigidly attached to the legs, the table would be as sturdy.
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