So many great choices for sleeping pads today. I remember in the 80s it was basically the blue foam pad until the original Thermarest inflatible came out. That was an amazing upgrade at the time. I’ve had an REI Helix (4.9 R-value, 3” thickness) for the last couple of years that’s worked well. Can usually find it on sale throughout the year for less than $100.
The 1969 trek can be typical of HI off trail hiking today. I can imagine what you endured. I soloed to the top of Mt. Wai'ale'ale through the Alakai Swamp and solo climbed out of Kalalau Valley from the near end of the Kalalau Tr to the Alakai Swamp/Koke'e SP areas. I look back thinking what managed risky endeavors they were.
Try hiking from Hilo to the summit of Mauna Loa via the ML Tr and bush wacking(mostly) to the summit of Mauna Kea and back down to the Saddle Rd in one water starved brushy trek.
Photography is almost always a priority for me - I plan my hiking destinations based on their photography potential. Therefore, 90% of the time it's a DSLR with a Cotton Carrier harness on my chest. Good system with quick access to the camera. I have added a couple of pockets for lenses and filters to the straps. Works for me!