48 star flag decal on WW2 Jeeps?

Hi guys. I am new to jeeps. Always been a dream to own a willys, not quite there yet. I'm picking up an 89 yj on Friday.
I really want to incorporate a 48 star flag.

I have seen some photos of WW2 with small flags on the lower right windshields. (see pic below).

Was this standard or something that the soldiers just did personally?

If it was standard, is there a specific size or placement?
I'd like it to be as historically accurate as possible.

I was just curious.
Thanks!

http://olive-drab.com/images/id_mbgpw_full.gif

Any ideas?