F550 Towing Capacity w/hazmat?

Im looking at purchasing a portion of my current employers business and stepping into my own career. Weve agreed on a price to distribute 3 of his products and I know the amounts that the customers take.

3 liquid products, ranging from 10.1 #/g to over 12.5 #/g in three removeable "megatainer" tanks on a flatbed truck and gooseneck

Im considering the F550 because most of the customers are smaller, less accesible plants down dirt roads and pastures. He wants to get rid of this side of the business because his class 8 trucks and tankers can no longer service the smaller accounts.

All 3 products are hazmat corrosive 8.1, by the way.

On Fords website, it says the towing capacity of the new F550 is 25,500.
With a 8000lb trailer, 3 tanks equipment, hose reels plus the weight of the product I would need to be right at 25,000 lbs everytime the truck leaves for its route, which would be three days a week.

But when you start "Build and Price" the F550 on the site, it keeps saying "Towing Max 16,000lbs".
Then when you get to the options page, the "towing pkg" says it increases GCW to 35,000 lbs?!
Im lost here. Can I put 25k behind a F550 or 16k? Anybody have any advice?

 

I should have mentioned that I need to have a 4x4 truck for winter use in the pastures to get to their day-tanks. Most of my mileage will be VERY short runs. Our monday route is less than 300 miles round trip with 7 - 10 stops. Tuesday and wednesday runs are less than 150 miles with 2 stops. I agree that the mileage would be better on a tractor but their overall size makes it really difficult to consider one for this setup. The International XT was the first truck I considered because of the 4wd option, but its nearly 50k MORE than a 550...

What else should I be considering in that size class besides the 550? I use a sportchassis M2 to tow the boat and i know for a fact it would be a dream to drive with 25k behind it, but its two wheel drive and absolutely, completely 100% usesless offroad. Half the boat ramps in the midwest are too steep or wet for it, I cant imagine trying to pull a sloshing load of chemicals on a snowy pasture road with it.

 

I guess Im going on bad information then.. I was told to steer away from BIG 4wd trucks because of the gas mileage would be worse than a loaded 550.

Is there any certain terminology I could be searching for to find some of these types of trucks?