tractordata = most likely pure tractor only nothing else, not even fluids (oil, fuel, coolant, etc...). this also means it is doubtful it includes weight of FEL (front end loader), and what ever attachment you have on loader (bucket, forks, etc..)
double axle = my opinion much easier to backup. vs a single axle.
you will need to pay attention to were axles actually set on tractor. to properly get your tongue weight.
12v winch sets you back in upgrading truck wiring if needed to deal with winch, and possible welding on a spot on trailer to attach winch. (being able to swap from trailer to unhook trailer and attach winch to rear of truck doing).
i assume electric brakes already going, with brake controller
trying to get tractor or car for that matter up on a "deck over" were deck sets above wheels of trailer. can be a challenge. more so if you are using a hand winch, (includes 12v winch as well).
a dove tail. does help out, being able to drive on/off trailer. it may not seem like much. but can be worth while.
if the deck sets between the wheels of trailer. no real need for dove tail.
your ramps can be an issue. from pull out, to flip up ramps. to ramps you store some place on trailer. ramps can be rather "heavy" and physical man handling them can put a person to there limit.
make sure you get some sort of "adjustable" legs on rear of trailer. that you can put down. so when you loading tractor or what not. the rear end of truck does not come off the ground. (makes for nicer loading).
tie downs can be important, beyond stake pockets. having enough on the sides that are accessible. makes a difference and less hassle when hauling who knows what in the future.
i am not a large fan of sides, on a trailer. or less some sort of lumber stake pockets or like metal stake pocket sides. tend to move a lot of stuff were having sides, means lifting it up and over sides every time.
i also tend to move small stuff. so being able to just "step up" without hiking your leg above your waist. and holding on nice and good trying to get up would be a bad thing for me.
the rare times i need actual sides on a trailer, generally when tossing on massive amount of tree limbs, and i gotta travel the actual road, vs just dumping tree limbs some place on the farm.
i really do not like sides, when just hauling lumber from local hardware stores. by the time i park and spot to unload, i end up dragging stuff of the sides, vs through the back of trailer.
with above said, some folks needs are completely different. and having sides means a lot less work. and holding in coolers, bikes, tools, etc...