I'd prefer the connectors on either end, so at 0 and 100mm. Height is not an issue, I think vertical connection will be better. I would prefer mounting holed at each corner, but two diagonal holes would work too. Thank you so much for this as well, you are such a great help! :)
@bobflux After thinking through the construction of the project, I have changed my mind on the connectors, I think a right angle is probably better.