The method I use for "climping miters on small items is;
Place a piece of masking tape glue side up on the bench, place the pieces to be joined on the tape, butting he long points, short side is up, press the pieces into the tape keeping the long points aligned, apply glue to joint, lift the far end of the pieces to cloe the joint, the tape acts as a hinge and applies pressure to the putside corner of the joint.
You can use a piece of masking tape to hold the joint closed as the glue cures.
Thought I shot pictures or a video of the process, cant find it now.
Looking at the photos from birdhunter, I'd glue the joints, let them cure then dowel them. The appear to be a design element, why fight them during assembly?
Strech wrap makes a great clamp also.
Tom