Okeedon has some very good views on this, he wrote in words what I was thinking but couldn't say as well.
Is this dealer a New Holland dealer? Then you are set. Take the weights, and enjoy your machine.
My only concern with all of this is that you will overload your front axle. However, you are in a situation where both the NH & BH dealers have told you what to do, and that your combination of loader & tractor will work & are right. DOCUMENT this situation somehow very well, and enjoy using your machine as is.
Should it break, it will have to be on their dime, as you got the go-ahead from both of them. (I would really kick & scream at this point, and demand it your way!)
For now, you tried, they tried, you wanted a cheaper loader with more reach & greater lifting. Neither of you is quite where you want to be, but in the big picture, you have about what you were looking for, if not exactly to the letter what you had in your mind. But, nothing is ever perfect, to get more for less, you had to trade off something, didn't you?
Take the weights & run. All loaders need rear weight, you are kidding yourself to think you don't. You might need more than you thought you did. Dad had (I still have) an old IHC H tractor with no power steering, narrow front, single-acting 900lb hyd pressure, 27 hp tractor built in 1949. With a loader. Dad made concrete wheel weights & a rear shelf for more. We run that thing with 800+ lbs of weight on the rear. You need the weights with any loader.
I think their offer to buy it back at 1/3 of new is a crock, that would tick me off as well, I wouldn't do business there. It would be a start if they asked for $1000. But to ask for 2/3, that's just wrong of them.
However, here is where you are. Take the weights & move on.
Look at the positives.
What Don said.
--->Paul