One other point in passing, as it has come up again...Follow me here, if you will...*if* the "heavy" insoles I put into your boots (and they weren't Baker's) were not noticeably stiff; *if* they did not crack "before their time"; and *if* they have given you a reasonable footbed (not expecting the same kind of footbed you would get with your approach), I fail to see the downside to using a thicker insole. I'm no "princess and the pea" but I don't want to feel every pebble, BB, and deer pellet underfoot. Frankly--and here I'm sure I will display the extent of my ignorance and wrong-headedness--I'd use a heavier (maybe not as heavy as a boot) insole even if I were making dress shoes. Again, I fail to see the problem...all things being equal.
I was thinking about this the other day...how does the welt fit into the boot "schematically" so to speak. If the insole is thin--roughly 5-6 iron--and no real feather is cut into the edge (maybe the edge is just beveled a bit) then the welt becomes an extension of the insole. Follow me? That's good...heck, it's even "elegant." But functionally, the inseam is vulnerable. Get too close to the vamp especially with a curved needle machine, and the inseam gets chewed up.
With a thicker insole, it's much like your scheme to split the insole in half and then glue it back together. The feather is cut to produce a "rabbett" into which the welt, theoretically, fits...again as an extension of the insole. The holdfast is roughly 5 iron, and the lip of the feather is roughly 5 iron, and the welt is roughly 5 iron...and it all works together quite marvelously. And, as a bonus, the inseam is protected by the feather and at the same time there is no "curling" of the feather to speak of. Love those bonuses! In my opinion, this approach...all things being equal (except the thickness of the insole, of course

Tight Stitches
DWFII--Member HCC