discovery4us,
Well Sir, We're fairly close in the setup you're thinking of. Our coach, an '04 Itasca Horizon 36GD with the 330HP C-7 CAT and Allison 3000MH trans, is towing an '11 GMC Sierra 1500 Extended Cab 4x4 and, in the bed of that truck is a Rampage lift, carrying a 900 lb. GL1800 Honda Goldwing. That lift, is right close to 300 lbs.
We've towed it on several smaller and one large trip and it's done flawless so far. We've towed (7) seven different Jeeps, one 2011 Honda CRV and now, the GMC truck and, while the truck itself weighs exactly 5300 lbs., it does not really put any more strain on that coach than the Jeeps or the CRV. The CRV tipped the certified scale right at 3700 lbs. The coach will slow down a quite a bit on some large grades, like the one just north of Bishop CA, to about 35 mph but, I'm not looking to win races with it anyways.
You should be just fine. Just make sure your base plate(s), tow bar, cables etc. are all rated for a minimum of around 7500 or more, maybe closer to 10K. Good luck.
Scott
Scott and Karla SDFD RETIRED2004 Itasca Horizon, 36GD Slate Blue 330 CAT
2011 GMC Sierra 1500 Ext Cab 4x4 Toad
2008 Caliente Red LVL II GL 1800 Goldwing KI60ND