In all sincerity,
~ I still strongly suggest you make it a shelf now, before it gets oddly balanced, scenic-ed, and with ballasted track.
~ As I said prior, a shelf layout, or, 'shelfie' now, needs to be just that at the get go...Your circumventing that, making a table layout first, is, to me, bass-ackwards, leave alone it's width sure don't look like it's gonna take to be resembling a shelf of any kind, which, in that case, you may as well add 4 legs, some X bracing and make it a standard table layout...
~ In finale', she looks too deep to become a shelf. ...if, IF you have the space, you could re-do-it before getting too far in, stretch it out twice as long, thin it out half as wide, keep same track-plan, and have a more soundly-shaped, shelfie... M