Given your height I think you would be fine on the 64" pad. With your head on the pad just your feet would hang off. The extra width is where you need to make the decision

I personally love the torso length wide NeoAir Trekker.
It doesn't crinkle, it is wide enough that my whole upper body is on the pad. So no cold arms when I'm sleeping on my back. It is super comfy.
I supplement with a piece of closed cell foam for insulation under my legs. The closed cell foam also acts as my pack frame. I usually go with 1/8" to 3/8" thick depending on the climate.

I use a NeoAir short pad and a sit pad for my feet. I used a Prolite short pad before that (both pads are 48" x 20").

I have never had an issue with my legs hanging off the end as the transition is pretty smooth (your legs sink down into the inflatable so it's not a 3" drop).

I also have a NeoAir large but I have rarely used it as the extra comfort of this large pad isn't significant enough to make me want to carry the extra weight and bulk.