Great trip report. Glad to see that you chewed all you bit off and didn't bail. That shows some chutzpah.
When I got back into backpacking, I was carrying the 40-50 lbs. of weight, but at least I didn't have to sleep on the ground 'cause I already had a hammock. You will likely get better rest from the hammock.
As for the mileage, it gets easier the more you get out, and the more you reduce your weight. I could barely do 5 miles when I started, but I can do 10 miles a day now without having to go to the emergency room. I hope to get up to 17 or 18 miles a day eventually. That's going to take increased fitness and lower pack weight. It's all part of the fun.
Now ditch that tent and lower your pack weight - no way you should be carrying 40 lbs. for an overnight. However, I admire you for setting such an ambitious mileage goal for your first overnight. Well done!