The chassis (if you built it according to directions) is just bolted together. The end plate is held on with 10-32s. You should be able to take it apart easily.
Cross-braces can be made easily with angle aluminum, or even more easily and consistently using
versaframe tubing (I'd recommend the 0.1" thick for this). As Billfred noted above, a rigid belly pan would be a must to keep the frame square.