When building deck for my new project I found impossible to use normal clamps because they must be inserted from above through very narrow openings. This is why I made small simple clamps using long M3 screws, pieces of brass tubing soldered together with small pieces of 2x6 mm brass rod, springs and M3 nuts. Fabrication and use of these clamps can be seen from attached photos. These might be useful for somebody else trying to find solution for similar problem.
