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.
"Success seems to be largely a matter of hanging on after others have let go." William Feather
"The use of traveling is to regulate imagination by reality, and instead of thinking how things may be, to see them as they are". Samuel Johnson