Floor jack under lower shelf lift till just clears floor. Or no shelf or as a addition to the bottom shelf a short leg that doesn't reach the floor in center.
Too answer the question about the bench having a vice or other attachment, or just with things on the table, before some one points out it won't balance.
When moving the table add something else laying around the shop, to the top to counter balance the table.
Should your table weight be permanently asymmetrical you can find the balance point easily by trial and error and position the short leg accordingly.
Many of my tables are made this way, though their is one in my shop that hasn't moved in 18 years, and 2 outside tables that get moved with the fork, that do not have these.