Yes you could do it that way, however you then have to tighten the T bolts from underneath the router table, which is not only awkward but on my router table imposible.
That's why I went for the threaded inserts and I use either all 3 of the holes in the LS base or only 2, depending on how far away I want to mount it (oops sorry shouldn't use that word:o)
It is a very quick and secure way of mounting the LS Positioner base.