You don't have to do anything really. Depends on your situation and how legal you want to try and be. It's still not a cut and dry science. 

On a gooseneck the front where the neck is counts as a bulkhead type object. 

As for straps and chains, when going over top of something connecting from one side of trailer to the other, the full working load limit is to be used. When you wrap it around the object it is one half the working load. Any chain not labeled is assumed to be grade 30. Any strap not labeled is assumed to be the weakest possible for its size. 

Looking at a few different brands of winch straps, I see very similar load ratings. Kinedyne is the brand I buy simply because the local place stocks them. 

2" strap is rated at 3,300lbs. Both 3 and 4" are rated at 5,400lbs. Another brand was the same but 3" was 5,000lbs. Why buy 4"? Depends on what you are hauling, you may need the larger footprint. 

How many do you need? Well the Feds say ever 5-10' regardless of weight or less than 5'if over 1,100lbs. Along with the double rule for the front if you have nothing to prevent bale from moving forward. So basically a strap over every row of bales.

The rule that trumps everything else is that the load simply needs to be secure and safe. You have to decide what's practical too. An accident can happen 1/2 mile from farm but I don't know many people who will throw that many straps to go a half mile. Most won't throw any. Some just the a couple. Some just flip the back bale so the rest can't roll. 

Another rule to mention is that straps are supposed to go inside of the rub rails if equipped. 


There are specific requirements for some specific products like steel coils, junk cars, logs, etc but nothing for bales. 

At the end of the day you can ask 20 troopers, 20 industry experts, 20 truckers and 20 people off the street and get about 100,000 answers of the "proper" way.