As you indicate, the battery cables usually present a clear access problem. I find it easier to remove the batteries about every 7-9 months, test, clean the batteries and the compartment, rotate the batteries (the one nearest the positive will always receive the greater charge and require more distilled water) and remount after cleaning all terminals and applying dielectric grease. Record the test results in your book for future reference.
After doing this preventive maintenance procedure regularly you will not have any worries about your batteries.
"LOVE and LOSS, are two of the greatest emotions one can experience. -- I went to school to learn about "WHAT GOES UP MUST COME DOWN" but I had to live my life to learn the lesson of: 'WITH LOVE THERE WILL BE SORROW'."
David Stewart. (after loosing my NAVIGATOR)