2003 Dodge 2500 Hemi towing improvement advice

Just traded my 2004 ram 2500 4x4 hemi for a 3500 dually diesel mega cab. I was pulling a 29 ft jayco lot heavier than yours I also had the 3.73 rear end. Are you running in tow haul mode if not do so. I got 7.5 mph only reason I moved up was to get more stability and better mileage. Had one hill on the way to Bristol Tn that I couldn't get over 45 with engine at 5000 rpms. Might be time for a tune-up with that wieght you should not be having issues.