Neil,
the only way to get an exact weight is to weight it as it is.
The
L3130 tractor weight is in the book. You must adjust for the wheels and tires and filling, if any.
The La723 weight is in the book. You must adjust for the bucket.
I don't know about your BH, I don't have that one, but be sure to adjust for the subframe, if you have one, and bucket.
Tip of the day...
the foldable ROPS has a serial tag attached to the right side upright that states maximum equipment weight of 7120# (this 7120# is from memory so be sure to check).
You may reasonably interpret this as the maximum weight when using Kubota attachments. If Kubota makes attachments to normally fit the
L3130, that when combined, add up to more than this number then the line of litigators will be long indeed in the case of a rollover injury.
So, bottom line, use the ROPS number. The State will likely use it too if they stop to check weights. Insurance may use it also.
I think your 10K guess is fair, considering your BH (doesn't take a sub frame?) but maybe a little low when you add the trailer weight. It's nice to have a little leeway.
All the best,
Martin