structural issues aside, the pushrod ends that you want to see through your acrilic window will be located at the upper surface of the wing above the main pushrod connected to the stick. It will be dark in there as well as obstructed view. the window idea sounds good but in practice is impractical. you would have to lay on your back on the ramp to look up into the wing and that dosen't even sound fun. just a note; that area where that bellcrank is located is the terminus of the fuel tank splice to the nose skin and the splice of the main skins and that area has a hole located there that needs that aluminum plate to hold it all together. this is just a museing but the inpection window you suggest should be on the top of the wing, this would eliminate all the afore mentioned problems.