UniStrut Frame designs

here is the spreadsheet, it lets you see the angle and force differences with different setups

you may also want to look at these motor mounts I designed New motor mount suggestion

for mounting the top beam and having it be adjustable, look at this post using a unistrut angle and short piece of unistrut to allow the top beam to be moved in and out easily

(lots of useful info in that thousand post thread)