I have a pair of Moabs a size larger than my foot. On longer hikes I wear two pairs of socks, Coolmax under merino wool. On shorter hikes I just wear the wool. The back of the shoe does get worn down but I've not had any blisters or hot spots on my foot. Recently I covered the worn spots with duct tape but that may make things worse and I'll have to try something else.
There are different ways to lace your shoes and boots to fix different problems. You want to try the heel lock. I tried to find a good video or diagram for Moabs but that was difficult, most showed boots or shoes laced differently from Moabs. I'm attaching photos of what should work if you find you want to lock your foot into the shoe more tightly.
First you run the laces from the top loops straight up to the top hole and then down into the hole.
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Then criss-cross the laces with the ends of the laces going through the vertical loops created between the last lacing loop and the top hole.
View attachment 183904
Tighten by pulling both lace ends down toward the shoe's toes.
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Finish with the standard double bow knot where the loops go horizontally (square knot style) not vertically (granny knot style).
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Good luck.