Began the process to trim the aft end of the J-channels to fit the fuselage. Read several accounts of people coming up short with factory dimensions, so I set up the tail section to measure them in place and make length to fit. Measured and marked the J-channels and cut to fit with the pattern from the plans. Channels ended up a little long and had to be removed and re-cut several times to make them fit correctly. In the end, they came out very close to the dimensions in the plans.