I usually avoid a straight taper from the handle to the tips on the back. Many bows were historically made this way successfully, but it gets a little too risky using a wood like Ipe . Instead I keep the middle section the max width for around 12". I have the tips around 3/8", but I measure in 6-8 " and keep this spot wider than a straight handle to tip taper. On a 1" wide bow I might use 3/4" width 8" out from the tip.
On a 3/4" narrow bow I might have it 5/8 or 1/2" wide .
I think Bowanarra mentioned in another recent post he does something similar to this too, with his layout.
Even so, with these narrow bows, especially when reflexed, centreline layout is crucial. You need to then get the bow to a decent brace height other wise the bow will want to flip itself inside out and de string itself.
At these early stages a narrow bow may actually pull dramatically to one side. You have to have gotten the tiller as good as you can, then you need to pull the bow at short draws, to the opposite side to train the wood to bend how you want it too.
Its crucial that you don't pull it back to far. Be aware the bow can also take set in a side to side orientation as well, as the regular string follow direction.
Now you have gotten the bow hopefully as good as you can, by training. If it still shows a list in one or both limbs you can only correct this by careful removal of wood. This part gets tricky, and as a whole subject of its own. I have talked about how to do it in earlier posts, so if you do a search on twisting bows, sideways twist you might be able to find it.
You want to do as much removal correction as you can without pulling it too far otherwise you won't be able to fully remove the sideways set.
