somewhat. You would end up using 2 backing plates, an upper and lower. you can see the lower screws on the backside but not the upper. There is another piece of wood that just covers the upper screws. I took a large flat blade drill bit ( I'm sure it has a name but I don't know what they're called ) and drilled out a section of that other piece of wood to access the screw holes. That other piece of wood just covers the holes right on the edge of the wood. Too close to the edge to provide extra support I thought. I ended up with just enough room to get washers in there. You would have to hog it our much more to get a backing plate in there. Another option would be to add another piece of wood to match the upper piece. Then, as long as you have room to drill longer holes, you could use one plate. More work than I felt was needed.
You're limited as to bolt size because the head needs to be recessed in the hinge. 10x24 is what I used. I believe The plywood is thick enough on its own to support the hinges if through bolted even with just washers. Obviously a backing plate would provide more support and it could be done. Time will tell but I think I'll be ok.