Hi Cajun. I have a Super C and I also tow a heavy trailer. My trailer weighs closer to 9000# when loaded. You need to find an RV built on no less than a class 5 chassis, however, with that being said, the older Seneca's on the Kodiak chassis had a lower tow rating due to the extensions on the rear to build the box on (or house, coach, whichever makes sense) and the smaller version Allison transmission. The Duramax in the Kodiak was derated as well and they lacked for power. That becomes a huge deal when towing through mountainous regions. You said you had some concerns about Nexus. I have been watching and learning about Nexus from their inception several years ago and I like what they are doing. factory direct does not mean you cannot get your rig worked on. They will pay another repair facility to fix any warranty issues you have and the best part is they are extremely reasonably priced. The Navistar Terra Star chassis or even the larger Dura Star will handle your trailer with ease and safely. There is an excellent write up on this forum from a guy who bought a 32SC last summer http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/28036931.cfm
This guy, Mike, has owner several RV's and explains the different models he researched in very good detail. I am towing with the Ford F550 4x4 chassis and am satisfied for now but have thought many times about my next move and since I do not have the cash to buy an EarthRoamer, the Nexus 32SC would more than likely be my next rig.
There is also an in depth thread on here about the Thor Super C RV. I looked at the Thor in person and there are many many reasons why I would not buy that unit but, this is why we have opinions. The household refrigerator will eat batteries very fast and unless you are always plugged in to 110/120 you will constantly be running your generator to keep your refer running. To me, our RV is to have creature comforts out in the wilderness and not be dependent upon electricity or whatever, and the Thor ties you to all of that. The thread is interesting, detailed and sometimes scary explaining many of the owner issues.
There is a 2012 Host 30' 4x4 on the F550 chassis on eBay currently. That is a very nice rig (same as mine) but it may not be big enough for you with kids even though it has 2 jack knife beds, but it will tow your trailer. You have the Dynamax Isata F series also, but hey are pricy like the new Seneca built on the M2 chassis. Unless you go to an A, your choices in the Super C are somewhat limited. I like the way the truck chassis drives vs a Class A bus type chassis. Also, if you take the class A pusher off of pavement you always have to be concerned about the air filter. Many pushers place the air filter directly behind the rear tires and when on unpaved surfaces, or race track infields, you will pull a lot of dirt into your filter. I have been told the air filter for a Cummins is several hundred dollars. So even though you might get a lot of bang for your buck with a Class A, they aren't necessarily built for exploring off of unimproved surfaces. Some A's do not drive very well on the interstate due to the CG being so far to the rear of the chassis.
Don't jump into an expensive mistake. Do as much research as you can and best of luck to you. My vote is for the Nexus 32SC with bunk house for you, but, it's not my money. Just friendly advise!
2008 Host 300 Super 'C'
2008 Ford F-550 Chassis
Diesel
4x4
Lariat crew cab
20' enclosed car hauler/garage
'87 Jeep rock crawler
Turbo'd