BoneJ - Trabecular Thickness with tilted images

Hello there,
Situation:
I have many images (of a bone) with a marked ROI in a tilted rectangular form. Like a brick standing in one of its corners.
I would like to measure the trabecular thickness (Tb.Th) and the trabecular spacing (Tb.Sp) of this marked region.

Problem
As the ROI is not standing on one horizontal line, when I do the measurement (in a zoomed in duplicate), it ignores the ROI and measures everything.
Clearing out the rest does not make it better, as it is going to count it as a large space for the Tb.Sp.

Maybe a solution?
Someone else had this same problem and posted it in this link and I asked there, but I did not get an answer. I was hoping someone could help me.
This is what he said:

Run thickness and separation on the whole image, then restrict your measurements to ROIs in the ROI manager

How do you do that?

I will post here my “solution” in case that there was anyone with the same problem and got here somehow.
It is not elegant, but it gets the (tedious) work done.
“Cntrl + d” marks the selected zone (with a grey line in the picture, so duplicate it). Now you can still see your selected ROI. Rotate the picture until it is right and then mark your ROI over the grey line.
It is a bad solution but it is a solution.
Hopefully this was helpful.