Concerning 105mm Micro-Nikkors of the Late Film Age: the matched PN-11 (52.5mm) extension tube has a very nice tripod collar. The foot print is tiny but this isn't a problem when it's installed on a Wimberley P-10/P-20 or similar Arca-Swiss style lens plate. It's not very stable on rubber or cork found on many tripod heads. The block of aluminum between the Nikon PN-11 and Wimberley P-10 plate gives room to install an older Kirkphoto macro flash arm under the fat 105/4.0 AI Micro-Nikkor.
On a modest budget the Wimberley C-30 Quick Release Clamp makes a nice macro slider. It's about 107mm long. Really Right Stuff makes some really nice macro accessories but they are out of my budget.
Please buy one of the Wimberley C-30 clamps because some years ago I asked Wimberley not to discontinue the C-30 and they said they wouldn't. I think I own three of them.
Dave
I'm not associated with Wimberley, Really Right Stuff or Kirk Enterprises. I am a satisfied customer of all three.