Newbie considering buying a Bison steel frame alum cover 10'SW 3H w LQ. Looked at numerous comments on this site on whether someone had "enough truck" but still unsure. Input appreciated on my calculations. Other haulers I talked to say I'm good to go, but... these goosenecks are new to me.

Dodge Tow vehicle

2006 Dodge 3500 5.9 Cummins 3.73 axle (single)

Gross Vehicle Weight – 7,313 lbs

Gross Combination Weight Rating – 21,000 lbs

GAWR Front / Rear – 5200 lbs / 6200 lbs

Curb weight            =7,313 lbs

4 people               =  550

Fuel                   =  180

Stuff                  =   50

Pin  weight say 15%    =2,000

Total laden weight     =10,093 (GVWR = 9,900)

310TE Trailer

Dry weight              =8,800 lbs

Water, say              =  300

Propane                 =   80 

Stuff /Tack             =  500

Horses (3)              = 3,400

Total weight of trailer = 13,080 (GVWR = 16,000)

Gross combined weight   = 10,093 + 13,080 – 2,000

                        = 21,173 (GCWR = 21,000)

In Saskatchewan, GVW of gooseneck trailer can’t exceed 2X GVWR of tow vehicle.

Over GCWR if fully loaded with 3 horses (likely only 2 at time, but capacity not there for 3?)

I believe that pin weight may be somewhat more than 15% or that 2000# number..... May be 30% or more... Weigh the truck and trailer on a CAT scale.

http://www.catscale.com/

Check out this thread.... http://www.horsetrailerworld.com/forum/thread-view.asp?threadid=11772&posts=10

It depends where you place the horses ( and other weight) in relation to the axles.   If the weight is ahead of the axles, then the pin weight increases. If the weight is behind the axles the pin weight could possible lighten.  Imagine a Tetter Totter here with the fat kid on the pin end.  If you put enough kids on the opposite end you can eventually outweigh the person on the heavy end.  If I was concerned about pin weight, my heavier horses would go over and behind the axle. So items like water and propane, you have no choice over where that weight sits.

Air bags can help with the stability of your load. But they don't really increase the trucks load rating.  The load rating is made up of several factors.  How much weight can the tires hold, how much weight will the lug studs hold, the bearing in the axles, the springs etc. By adding air bags you have helped the springs out, But done nothing to help the tires, bearings, studs etc.  Also your truck is rated at being able to stop and start a certain load. These are stressed the weight puts on the drive train as you start into motion and the brakes face as you try to stop motion.  Now some of these spec's are capable of supporting greater load. But most of us never see the engineers calculations to understand where the weak link is.  The truck makers take all the engineering calcs and develop what they consider is a safe working load that is lower than the weakest link. We read about folks exceeding the load capacity all the time, They are basically beating ( possibly with their life) that their truck is able to exceed the what the engineer designed.

By adding airbags, helper springs, tires with higher load rating etc you may actually improve on what was the designed weakest component and improve you trucks load rating. But who is doing the engineering calculations to tell you what the new weakest link is and what weight is the new max?

Painted Horse's explanation is a good thing to wrap your mind around.  I will add that 10' short wall makes adding weight behind the trailer axles to reduce pin weight a minimal gain.  Your main issue is the truck's rear axle weight rating. 

You will always hear people say I pull "X" with my "Y" truck and do well.  The dealers are also known to say anything to make a sale.

I've very seldom hear people say I pulled "X" with my "Y" truck and it was a Dumas choice.  I do read about them in the news or obituary section.