Sadly, a Paladin level 40, with great skills is still a level 40 character with single target capability.
I don't want to rain on your parade but I would rather go for a realistic approach.
You can definitely get level 50 playing in a healthy way (around 2~4 hours), or somewhere around 55 if pushing for a even longer playtime.
Paladins are hindered by their single target up to level 150 where they'll be able to properly use aoe (area of effect) attacks.
I'm not counting burst arrows as they're expensive and the area is only around the targe.
I would suggest going on a nice dragon hunt, enjoying the game for a longer period of time, as play time seems to be tight to you but the goal is to have fun, preferably in a healthy way.
You could go for dragons in yalahar, maybe then cults to get some profit, edron vampires or even vamp hell, putrid mummies on dark pyramid (exanima), maybe even giant spiders in plains of havoc.