Aaron, they make a 2.313 paddle also. #9979 is what I ended up with, 162x16x2.3 but that was mostly because it was cheap. I ended up getting some Vanamberg drop brackets that are about 1/8" thick. Hopefully they will be strong enough. Plenty of people seem to be running the 16" tracks in stock tunnels, and width is going to add more surface area than length increase. I bet you would regret not going 162 in the long run, there is only 1# difference in track weight between 159-162.
Anybody know how much weight can be safely removed by drilling the track? The larger Camo extremes are among the heaviest.
Let me know what the tunnel extension ends up costing, I can't figure it out from the Hartman website. It looks like the prices quoted include the rail extensions.