Hi Brian,
Whatever the background, if it is too close to the subject, it will be;
a) lit almost as brightly as the subject and
b) almost as sharp as the subject
c) show the shadow the subject casts on it
These are things that will divert the viewer's attention away from the subject itself.
Another suggestion, based on this image, is to consider a little 'fill', all it would take is a bit of white card propped up to reflect some of the light into the shadow side of the subject.
It is good to see you continually expanding your range of shooting, I may not comment on every thread you post, but I do view them all.
All the best, Dave