Ran the first trial with thorn resistant tubes. Due to heavy rains, most of the trails were muddy, and I totally avoided the thorny section of the trail that has been causing me most of my problems. I didn't seem to notice any difference due to weight of the back tube. My daughter is getting heavier, and the mud bogging down the bike cause most of my difficulties. I was pretty exhausted by the time I hit the thorn section of the trail, and avoided it completely, choosing to bike on asphalt and road instead.

Note to self, really crank down the seat post.