Grape Vine on 4x4 post - should I space it out?

I have some grape vines planted on a grape arbor I built.

The vines are intentionally climbing up the 4x4 ACQ posts.


Grape vines can get fairly thick over time. I'm wondering, as I wrap the vines around the posts, should I space them out a little bit with a scrap of wood I can later remove as their stems expand?

How much of a spacer should I use? 3/4" or a 2x4 (1.5")?
I figure I just need it on two sides of the post, not all four.

What do you think?

Here's a picture of what I'm talking about: