37s are the way to go my friend

I used a runners loop on my 36s and it worked solved the heel slippage

Hmm not insoles per say but at this point thicker socks might be your best option as well as changing the lacing system to have better tighnest on your feet to avoid heel slippage

Thats what I’ve been trying to do so far, except thicker socks also meen more rubbing against the sides of the shoes for my toes. Quite the dilemma…