99 Ram 350 Rv

I have a van motorhome made from a '99 dodge 350 van. I got a sweet deal in 2002 since it only had 2,500 miles on it and it was already 3 years old. (it didn't get used a lot). Since then, we've put around 28,000 miles on it. One thing I'm finding is that it really eats up front brake pads. I replaced them at 19,000 miles and they are already half gone again. Seems pretty short to me. The rear brake shoes still look almost new. But the vehicle is heavy - 9,000 lbs. GVW all the time. Does anyone think the weight is the problem? Because it sat for three years virtually unused, maybe the front disks got pitted from rust, but they look smooth now. Are there any specialty brake pads available that may last longer? All the parts dealers I went to last time I did the brakes only had one type pad for this model.
Suggestions anyone?

You can change the brake bias buy swapping out the proportioning valve to an adjustable one, or to a vixed valve that is biased to the rear brakes.
That should cure your problem.