Me, I wouldn't ever consider an aluminum trailer for anything. More prone to cracking at the welds or severe stress points and when they do crack, they are hard to repair as they have to be very clean and not everyone can repair them. I say that as a welder for almost 50 years with both steel (majority) and aluminum.
As for the design "channel tongue" another nope, go with tubing. If you ever get into a situation where it's loaded to the max or on a rough road, you're looking for cracked diagonal braces where they're under the front edge of the deck from flexing. IMHO the best style of tongue is one that is a single center tube that goes back two preferably three bunks and two diagonal braces (same idea as what they have now) from the coupler back a couple of bunks either side.
ST tires, I'd go with LT tires, something with some steel belts, not just all nylon.
Just my two cents (1.5 canadian

) worth