Baffling questions...1x12 build...

DarnWeight

Building a 1x12 cab in full Vox livery to match up with my new Vox AC15CH head, and have a few questions...

- Got a smallish piece of very nice 15mm baltic birch ply for the baffle.  With a baffle of this thickness/stiffness, is mounting the baffle as a floating or a fixed one going to make any difference to the sound/response?  Cabinet carcass will be 18mm softwood shelfboard, if that makes a difference.

- Cabinet will be open/semi-open back (speaker is a Fane alnico), and I'll be front mounting a separate frame with the tolexed panel and grllle cloth. The baffle will be screwed into cleats/supports from the rear.  If I just float the baffle along the sides, is there any reason it has to be cut to the full internal height of the cabinet?...i.e. Can I leave sizeable gaps at the top and/or bottom?  I'd guess with it being open-backed, that it shouldn't make any difference.

Already built a few cabs before, and happy with all the ones I've made so far.  Really want this one to compliment "the Vox sound" and want to get it looking and sounding 100% right.

Cheers!