Re: Trailer ramp/gate design opinions.
The first set of ramps are the ones I'd have the most faith in, but they could be improved yet. I make my ramps out of 3/16 thick x 3" tall formed channel with 3/16 thick x 2"x2" angle iron. I only put expanded steel on if I have little tires (lawn mower size or smaller) on the ramps because it makes the ride smoother. However, a truck tire will cause the expanded steel to sag quickly. Remember, you simply cannot put too many welds on a piece of expanded steel... the better it is tacked down, the less it will sag.
As for square tube stock, I'd still prefer formed channel due to the strength. Think of your floor joists in your house. Would you rather have a thin and tall (2"x12") floor joist or something like a 6"x6" floor joist? With the 6x6, you do get strength, but a floor made of these is still more likley to sag than one made from 2x12's Now, if weight was an issue in your home, as it will be on your trailer, the choice is very simple. With the tube steel, there is a lot of steel that will not actually be supporting the load you are driving over the ramp. Instead, that extra steel is just useless weight you will be picking up every time you have raise or lower the gate.
If formed channel doesn't suite your needs, consider making it all out of angle iron. The same basic principal applies. I'd just like to see you use something that is going to give you the maximum amount of strength for the amount of weight put into it.
As for the six cross tubes on the second gate, those are what is keeping a vehicles tires from falling right through the uprights. The expanded steel would not hold up very long if it did not have the structural support of those cross bars. The flat stock cross bars on the first set of ramps are likely to be stronger, but I can't quite tell what size they are