I'd recommend getting the DRW for the purpose of hauling the camper. Even with my mid-size Northern Lite w/o AC, generator, microwave, slide-out, w/o large holding tanks for boon docking, without all the space one might want for spending a lot of time in your TC, without all that extra stuff I am still a couple hundred over the GVW of my DRW truck.
My camper is probably even lighter than the one you have in mind with your built in generator, large holding tanks for boon docking, A/C being from Texas, maybe a slide or two for roominess because you'll be using it a lot, etc.
Could I haul my camper on a SRW truck? Probably, but not without a lot of extra money spent on upgrades. Even with that I wouldn't feel as safe and stable as I do now with my DRW. With suspension mods, wheels & tires, etc, you could spend several thousand dollars extra on a SRW to haul the type of camper you're after.
Personally I bought my truck for the camper completely disregarding any negative aspects of using it for a daily driver. Rather than spending several thousand dollars on mods for a SRW truck I bought a used Accord as my daily driver for $2000. Now I don't have to think twice about how I'm going to park my daily driver (the Accord). The other benefit is the camper is always loaded and ready to go camping at a moments notice. I've probably already recouped the $2000 I spent on the car in fuel savings & repair costs not having to drive my truck everyday.
Things changed for me this month though as I just moved to Oregon and I can't get my car over here yet. I am using my diesel DRW as my daily driver. I start it up and less than 5 min later I am pulling into the work parking lot shutting it down before it ever gets warmed up. I hate doing that to it but it's a bit too far to walk in the winter. I don't have a parking garage to deal with but it can still be a challenge fitting into the parking lot and then worrying if someone else is going to hit my truck. I hate using my truck as a daily driver, I miss my car for that.
I would never buy a DRW intending to use it for a daily driver, but I'd never buy a SRW to haul a truck camper either. I wouldn't try to take my car to the places I take my truck & camper and although I can go most places with my truck that I take my car it isn't as pleasant. I always try and use the right tool for the right job.
The truck being too long won't be as much of an issue as the camper being too long if you plan on taking it off the beaten path. My last camper was 12' long so the rear overhang and thus departure angle limited the places I could go without ripping a rear jack off. My current camper is much shorter therefore allowing me to go places I couldn't with my last one.
If you get a short-bed truck you'll have much more overhang for the same floor length as a long-bed truck. A large short-bed camper will have more problems offroad with the overhang than a long-bed camper of the same length. You'll also be limited on the choices of camper you can get on a short-bed truck. You'll have more options if interior room and floor plans are important with a long bed truck.
Consider any toys (motorcycles, ATV's, boats, etc) you may want to tow. Having too much camper overhang requires expensive hitch systems to safely tow. A 9' camper in a long bed will have significantly less overhang, thus requiring less hitch extension to tow, than a 9' camper in a short bed truck.
I agree with you that the 8' extended cab is the way to go if you know you'll never have a rear seat passenger bigger than a little kid. I use mine for storage mostly.