I put a performance tuned ECM and a high miliage low rpm clutck kit on my Ranger northstare crew ultimate. I also run 30 inch tires. My goal is to increase gas miliage and decrease noise. Clutch kit is smooth and power for hills is fine.it is much less noise.you sacrifice some snappiness but its...
Try a regular battery charger, charge for a couple hours. Measure the battery voltage with a meter after charger is disconnected. Maybe your battery tender is junk leading up to you original battery failure. A fully charged battery should read well over 12volts
Bring the stat down at night. If you have central air I'd leave it so it runs just a little during the day to help with humidity.
It will also help that your system won't have to work as hard at night when you crank it down.