I've built six Old Fogeys in the past three years, it's an awesome design for relaxing evening flying!
I think the most important mod you can make is to reinforce the landing gear BBQ skewers. I take popsicle sticks and drill holes for the BBQ skewers to pass through and then glue the popsicle sticks to the outside of the airframe. It spreads the load on those BBQ skewers and adds an extra layer of material.
While you're at it, reinforcing all of the BBQ skewer holes is a good idea. I use little squares of old gift cards with a hole drilled in the middle, glued on the inside of every BBQ skewer hole.