OK, a little history. My first motorhome was a 94 class C with the Ford 460 & automatic. Don't know the automatic model. It was a 22 ft Jayco. The reason I went with the Ford was because in the shorter class C's, chevy only offered the 350 whereas Ford offered the big block. That unit had a 4.10 gear. When I first purchased it, I was towing with an 18" flatbed, Jeep and toolbox on the front. 7500 gvw trailer and it was pretty much maxed. My jeep trail ready weighs out at about 4600, the trailer was titled at 1800, trailer spare at 75 and all the stuff in the tool box gets you close to 7000. Never a problem.
I then bought a 24' enclosed trailer. One big heavy sum bitch! It was a load but the engine seemed to do OK. My problem came when we went down south in the middle of July. With the van style front end, AND ONLY AT LOW SPEEDS, I couldn't keep the trans temp down. I had specifically added a trans temp gage and I was glad I did. Going into Crawford's camp at Tellico I had to stop halfway up the grade to let it cool down.
I came home knowing I had to do something different.
Next came the new motorhome. It is a 99 Itasca with the Ford Triton V10. I wanted a deisel pusher but the price difference was too much. Quite frankly I went with the Ford again because it is the most common and I talked with folks that had them and liked them. The big push for a new motorhome was not for the towing capacity. I planned to reduce the trailer size to handle that. The bigger reason was 3 fold. First, the passenger seating in the class C front end SUCKS. Period. Small foot room and the seat couldn't recline because the dinette was right behind it. Second, with just the wife & I, we wanted a rear bedroom rather than climbing up onto the bunk over the driver's compartment. Third, needed a generator. We have a cat and dog that travel with us and in the warmer areas, you can't even go into the grocery store without heat being an issue. We wanted to be able to run the generator for the air. The other need for the generator is stopping in truck stops to sleep. Air, coffee and microwave are really NICE. Ours is a 32 ft.
We then bought a new 20 ft enclosed trailer. It is much lighter. If you ever do an enclosed, IT IS A MUST THAT YOU DO THE EXTENDED TONGUE. Otherwise you can jacknife the trailer into the motorhome. (you know that thread going on about how do I know this???) Only broke a marker lense thank God.
The new motorhome has a 5.13 gear. Ironman's is also a 99 or 2000 with the Triton but his is a 35 footer. His gear ration is 5.38. So, top towing speed with these babies is about 65 mph. I put a trans temp on this motorhome and have yet to see a problem. Time will tell.
Regarding towing capacities. I could not find any manufacturer that would put on a hitch capable of 10,000 trailer weight. So, we modified and beefed it up. I had to do it on my class C and Ironman had to do it on his. KB8YMF also has the same chassis as me but I think he is using the factory hitch since he is towing a flatbed trailer. Figuring towing capacities goes like this. Inside the cupboards of the motorhomes is a sticker with all the weights and capacities. (water, fuel, towing, dry weight, etc)
Your vehicle has a vehicle weight which is the weight of the base vehicle. I think mine is about 12,000. The GVW which is the weight of the motorhome fully loaded. I think mine is 18,000. So, I have about 6000 capacity for food water, passengers, cargo, etc.
Next it has a CVW which is the combined vehicle weight. This is the weight that the total rig can be. I think mine is 24,000. So, subtract the 18,000 from the 24,000 and you have the weight of the trailer. You will see that I am only good for 6000 pounds and my total trailer weight is close to 8000. (all these numbers are from memory) But there is a bit of a play on numbers since I am not necessarily loaded to my max 18,000 in the motorhome.
I actually need to get the entire setup weighed to figure all this out a little bit better. And of course, never forget your trailer brakes.
Mileage. With both motorhomes I get between 6 and 7 mpg while towing the jeep and close to 9 empty. I have the Banks exhaust & intake on mine & I just did a performance tune. I have driven it without the trailer after the tune & it looks like I am getting over 10. (watching the fuel gage) So, I am curious to see if it improves when towing. Headwinds make a huge difference in mileage. Seems like every Friday when we go to the dunes the wind is out of the west and when we come home on Sunday it is out of the southeast. Go figure.