If you're getting it built I agree more d-rings, my 25 ton tag only has 6 I believe on each side, it's a pain. For lighter stuff like buckets you can hook on the bottom of the outside lip, but not ideal. I really like the deck height of the 17.5" tires, it makes loading so much easier. That's a nice length too, mine is 34' with deck and beavertail and it's pretty long, I wish it was 4-5' shorter. Nice for having the room, but getting around tight residential areas is more difficult.
A tandem will haul like a dream behind a tandem dump truck. I pull a 25 ton triple axle with a 210 volvo on it behind a tandem dump truck, and it's pulls nice, only complaint is truck is under powered to pull the weight.
Also depending on what you're loading, I really like having a tilt deck, beavertail and ramps. It makes loading a dream. I remember the first time I loaded it, pitch dark snowy icy deck, and muddy icy tracks. A perfect combination for a bad loading situation with many trailers, but with no break over point and such a low loading angle, it's a non issue.