...look carefully at the design, and ask yourself, "Can this actually be achieved?" I'll argue it cannot. I'm not trying to be negative here. Fact is, from my perspective, the design cannot even work as a two-person craft in-universe.
Most of the design is perfectly fine. It's when we get to the gunner's seat that we run into problems. Dak is shown in ESB sitting near (within arm's length) of the rear window. There's not enough room there for a second person, unless he's a contortionist. The pilot lies down comfortably (though one can argue that's not especially effective for a dude who's flying a combat vehicle). The gunner would have to be almost standing, only there's not enough height for him to do so. The only way he could fit would to squat in an incredibly uncomfortable position, where his only concern would be "Where can I get something to take my mind off the throbbing pain in my thighs and calves?" as opposed to "I need to shoot this AT-AT!" (Also bear in mind that there are what look like some sort of cooling or heating coils in the rear of the speeder, which would presumably take up a good chunk of space inside.)
Design issues in the movie notwithstanding (let's imagine the gunners either are highly trained to deal with the cramped quarters, or humans in the Star Wars galaxy aren't built with the same pain receptors we have), there's no way to fit an action figure into that space in a totally accurate Snowspeeder. The cockpit is shown only opening at the one hinge; forget how tough it must be for a human to get into that second seat without totally kicking out one or two major systems, it's tough enough to get a figure into the existing Snowspeeder. Make it smaller, and how are you going to get Dak (or Janson, or whoever) in and out? Even with added articulation on the figures, it'd require an additional opening on the Snowspeeder, which a lot of folks won't like. They could go for a permanently affixed figure (maybe just the upper body), though this proved unpopular with the Cruisemissile and Power FX X-Wing.
I don't see any way the new Snowspeeder can really be entirely accurate. The gunner is going to have to be placed in through a different hatch, or he's going to have to sit a bit too far forward. It looks better than the existing one, true, and I'm not complaining--fact is, I never even realized how physically impossible the Snowspeeder is in the movie until today. Just saying, is all.