Cool and all, but really not needed.
Virtually all bikes have a curved top bar.
If the studs fit around the bar all you do is prop the front and back up with foam or cut sections of grips until the middle part is above the bend, and tighten the tank down until the middle touches the tank.
If your top tube is the right width but way taller than your tank studs reach, just use stand-off spacer nuts and new bolts to go up through the bracket to them like this.
If your top tube is too fat to let the tank studs by, no biggie.
What I do for that is a bit complex, but it works well...
I have topics about this somewhere, but in short, I drill a hole in the tank brackets in the center, matching holes I Tap on the top of the tube, and mount the brackets the same way they face on the bottom on the top to the top bar.
Do the usual foam/grip supporting of the front and rear of the tank and tighten it up.
Whack off all the extra tank stud thread and you have a nice clean look to boot.
THIS NOT NOT IDEAL!
Though the tank mounts to the 2 brackets in 4 spots, they don't have the natural support of the fame to bind to, it's just a taped hole and bolt for each one.
For a street bike you don't wreck much it's fine, beating it up though and smash that tank around and it will fail.
I have no problem with the extenders though, that is common enough.
Personally, I am really into the new gas tank frames now, it's already a part of the bike.