Skyranger, I have a 57 Pacer that I used to have to do a punch test on the struts periodically. Seems like we used a fabric tester and overlaid the bottom of the strut with 1/4" grid paper. Then we punched each square to the limit of the tester and looked for any deformation. This test was done only at the lower foot or so of the strut. I wound up fixing mine by replacing my old struts with new sealed struts. The thinking is that if internal corrosion is taking place, it will be at the bottom where water will collect.

Like you I would be more comfortable if I could see the entire inside of the strut. Some of those borscopes do have extensions that you can buy. I know when I bought mine 10 years ago or so, extensions were available.

If nothing else, you could punch test the entire strut.

Best of luck,

Tim