Mike, the change /adjustment to tail might possibly be one of those "blessing in disguises"
I honestly don't know how much of an effect the tail has on bikes, no certain how effective or in effective they are at reducing drag and or increasing stability
But...you will be adding surface area to the rear, and raising it, hopefully it helps with the air coming off you and the front of the bike
I think its common to assume it will help, but as with most assumptions it's a crap shoot imo, until proven out, there are a lot of bikes that are very stable with minimal tails, and nearly naked, and many bikes that are struggle with swoopy body's
At any rate, many find some gain in speed when butt raised a bit, your adjustment in height will be near that region, so hopefully this helps, you may consider an assortment of removable tail fin configurations that can be readily swapped out in your quest to find more speed