Have you pressed the gravel or did you press it when you had it laid? All the above suggestions are great, but one that hasn't been mentioned yet. It sounds like your issue isn't your truck setup but the road - and since you own the road, I'd suggest having a contractor w/a steamroller come and press your gravel. It will help A LOT with traction (well, unless you get a lot of snow/ice in which case it will hurt your traction in the winter). Speed and bouncing and 4LO never are good in the long run unless you like breaking things
Also, there are other options - you can self-apply asphalt filler that will help hold the rocks together, or you can get a trailer full of dirt and spread that out over the rocks and water it down (helps act like a sort of cement). Honestly, if you use the road regularly, I'd focus more on the road than the driving technique - not a lot you can do if the road sucks