I would start with handles on the middle section, as Fazz said. The garage door handles are cheap, and you can attach them using the existing bolts so no drilling is necessary. Make sure the sections are not out of round, and bend the door, if necessary, to minimize leakage. Then I'd cook with it a while to see if anything else is really needed. Choose your mods based on your own experience, don't just rush to create what other people think is the "hot setup". I consider wheels and the lid hinge to be worthwhile conveniences, and gaskets and other attempts at making the WSM air tight to be unnecessary overkill (just my opinion after cooking for 15+ years in a WSM without them).