Need help fudging a group in 8039
Might not be ideal, but have you tried replacing each Crossblock 2x3 with a Crossblock 90 and a Technic Lever 2M?



You lose a little bit of stability on the bottom edge with only two pin connections instead of four, but I think it'll do the job just fine. The new parts list is then:
 2x Crossblock 90 Deg
 2x Technic Angle Beam 4x2 90 Deg
 2x Technic Lever 2M
 1x Cross Axle 3M
 1x Cross Axle 5M