I live in Michigan and we get similar temperature changes, and I can't understand a truss rod needing frequent adjustment unless the wood of the neck is real junk. Having bought a number of new basses, I have come to expect having to adjust when new, adjust after 6 months, maybe a again after a year and then the neck should be fairly well set. Changes in string gauges or other hardware would make further adjustment understandable.I think it depends on where you live. A MIA maybe not so much. I live in Minnesota. We get major temp changes. My CIJ & MIM have had to be tweeked about 3x each in the last four months. I do like my action low so any change is noticeable. Also I change strings and clean my frett board a lot and adjust with new strings.
My $0.02 on the access hole. Finesse it a little better and paint. Sand that little divot on the end of the fretboard smooth and go back to playing....can't imagine you spend a lot of time fingering down there.
Final thought - current owner can do what they want. Smash, set on fire, use for boat oar....
