Congratulations on your new truck.
I basically did the same thing you did. After trying to make the 2500 SRW work I upgraded to a 3500 DRW however even it wasn't as safe as I thought we should be. After several years I started looking for something better to tow our 15,000lb 5th wheel with. I decided against an HDT due to my wife not being able to climb up into it.
She fell in love with a Chevy 4500 DRW with the duramax diesel and allison transmission. The truck had been upfitted by Monroe with an air ride cab, seats and rear Link air ride suspension. This is a dream to tow with. It is stable and handles the 5th wheel with ease.