What do you mean by "slideout?"
Are you talking about "slides" which are sections of the camper that extend from the body to provide more living space?
Or, are you thinking "slide-IN" which is less-common name for a truck camper?
If you are willing to go with a lighter, less appointed camper, you can easily do what you want with no suspension modifications at all. There are many truck campers in the 8' floor range that have all the basics (i.e. bed, bathroom, kitchen, TV) that don't have slides and will run in the 3000lb range loaded, leaving you plenty of payload for a 5000lb trailer tongue.
I'm getting to the point where I'm about to say "ratings be damned." We've got people running around with 2500lbs on F150's, 5000lbs on F250's AND towing a trailer... They seem fat and happy, so apparently the ratings mean nothing.