Which lift for pulling?

So I spent a little time in the threads, and there is so much great information about lift kits that it is kind of mind boggling.
Here is the question I pose to the great minds of TX..
I would like to lift my truck ('05 Prerunner DoubleCab) about 2-3".
I would like a lift that keeps most of the good highway characteristics as stock, as I drive @100 miles a day to work and back. I would also like a lift that won't sag like a dog with worms when pulling a trailer.
I will be buying a 16' lowboy at the end of this month, and will be putting a couple of semi-heavy loads in it to get rid of some scrap iron. At the mid-end of this year however, I will be buying a new Polaris RZR, and the smaller Polaris for kids, so me and the wife and my boys can go have fun. This load will get pulled quite a bit, but I don't believe it will be that heavy.
I don't do a whole lot of offroading, but I would like to be able to cross a steep ditch if I needed to, and drive "quicker than slow" thru our pasture. (anthills, cow manure hills, and cow ruts)

What would be the best lift to get with this combination of activities, with the price staying around $500 if possible.

Oh yeah, I had my truck on stands the other day (placed on the rear axle) and it seemed like my leaf springs were just about flat across their length. Not into negative arch yet, but probably not to far off.

Thanks in advance people.