With regards to measuring, here is what I do:
When it sits against the side of the container, very easy to measure obviously, but when it is sitting flat on the ground, I reflect a ruler against the glass / perspex. Not precise, but it never is. Benefit is that you don't bother the T, you don't have to remove it from the enclosure or handle it in any way.
Hope this makes sense.
Excuse the crude picture :blush: , can try and do a photo when I get home if you want.