I do the following:

Take a piece of 3/32" or 1/8" wire about 2" long and solder a ring terminal on one end (an 8-10 stud ring terminal is just right for a 4-40 bolt). The wire is then (in your case) inserted into a drilled hole in the MAIN strut and epoxied in place. In the fuselage put a blind nut in the appropriate position, then use a 4-40 bolt to secure the strut to the fuselage. Do the same thing for the other end of the struts where they attach to the wing.

I normally use K&S streamline tubing for my struts and JB Weld the wires with the ring terminals in the end of tube. I also fasten the joint where the 2 struts meet with JB Weld. It takes some sanding/filing to get the joint smooth, but the end result is a strut that is very light in weight and quite strong.