If you have a larger wing I'd lengthen the boom for better balance.
Start by making the length of the plane at about 80-85% of the wingspan.
So if the wingspan is 20 inches the length of the plane from nose to tail
should be around 16 inches.
I know many will disagree with this but that's how I start.
Jets I do different. On a jet the length is greater than the wingspan because
the chord is greater.
Adding to the boom length means you might have to add more weight to the
nose unless you find something very light. Try a carbon fiber tube. I was using
a BK soda straw there for a while which worked fairly well.

Ha, Skoda!