Question about axle Ratios

Check the available payload on the yellow sticker! Ram's generally have the lowest payload capacity of the half tons and 8000 lbs is really at the outside of what most folks would tow with any half ton. From a quick playing around with the RAM towing guide a 4x4, crew cab, 6' box Laramie with the hemi only has 1,300 lbs of payload capacity which means after even one passenger you're looking at a max trailer weight of ~6,500lbs. A quad cab 4x2 Laramie with the short box might work for the low end of your range. As far as the 3.2, forget it, even Dodge doesn't rate that at 8,000lb and they're assuming a much easier tow then the barn door that is a travel trailer.