Current versions, weights: Micro Nikkor 60mm is ~460 grams, Micro Nikkor 105mm 790 grams, Micro Nikkor 200 f/4 1,180 grams, Sigma 150mm f/2.8 OS also 1,180 grams, Sigma 180 f/2.8 a whopping 1,630 grams.
I know my choice would depend on whether this would be a multi-day backpack journey or whether I would be making day hikes from the car, also on the elevation for each hike, how much other camera kit I wanted to take (tripod if shooting non-macro or if shooting formal focus-stacked micro, the "Lord V" method with a hiking pole if shooting only one-shot macro), and a realistic assessment of my own fitness.
Extension tubes: all air is equally good optically (well, don't blow smoke in your extension tube..
). Select for strength and precision milling. I wanted to use extension tubes on a 400mm telephoto (in addition to the 1.4x teleconverter, which is the most efficient way of increasing magnification on a telephoto lens), I bought the very sturdy and well made three-ring Kenko set (62mm total) at ~$200.00.
Folks, the worst has happened. I now have GAS and associated nerdiness in two areas: photography and camping.
All hail to the scale! Realistically, since I weigh 115 pounds, I do have to be picky about gear if I don't want to exceed the 1/4 your body weight rule. I have tried 1/3 my body weight, and it wasn't pretty.
You 6' 2" guys in the 180-200 pound range can "afford" more gear.