From another 4x2 converted to a 4x4, here's a few things you can do (other than those mentioned, above). Like you, I wasn't in a position to trade to a 4x4 when I wanted to, but eventually things swung my way. Until then, I used the following tactics to help off-road:

1. Buy really good all terrain (A/T) tires. Long Trails (assuming that's what your truck has) look a little rugged, somewhat luggy, etc., but they have a hard, long-wearing rubber compound. Trade up to some BFG A/T KO's or Bridgestone Dueler Revos. Avoid buying mud terrain (M/T) tires, even though they look like they'd do even better (they will, to some extent), because you'll just be tearing up the trail.

2. Buy a decent air compressor that will run off 12V. Carry it with you. Also, invest in a good tire gauge (see #3).

3. At the trailhead, air down to about 15 to 18 psi. That'll gain you some more traction than you would get at street pressure. You could optionally leave the fronts closer to street pressure (say, 28 to 32 psi), but the lower air pressure will let the fronts roll over sharper obstacles better. Lots of goopy mud would be a good reason to leave the pressure higher in the front. Sand is an excellent reason to lower them down.

4. Disconnect or remove your rear anti-sway bar when off road. OPtionally reconnect or reinstall it once back on pavement. The jury is still out on how much a disconnected or removed rear anti-sway bar affects the ride quality on road. Mine is permanently removed. If you have a lift, though, you will miss it more than if you are at stock height.

5. A winch bumper (such as Shrockworks) would help with front approach angles and, amazingly, to hold a winch. Never hurts to be able to pull yourself out. Plus a winch bumper looks much cooler than a brush guard and/or the stock plastic bumper.

6. Remove the mud flaps and step rails (temporarily or permanently - your choice). If permanently, you can get some good money for the step rails on Ebay. They're relatively cheap to ship, too.

7. Carry plenty of recovery gear. Straps with loops, not metal hooks - buy from a 4x4 place, not Walmart. Have a recovery point front and rear (tow hook on the front frame, Class III hitch reciever in the rear works well). Take a shovel with you, too. Bring water, extra socks and shoes and invest in a set of rubber front floor mats with deep grooves to catch the junk and protect your carpet.

Hope that helps.