Since you already have the source images, may I suggest stacking the 4 sessions separately then stack the four results. It may work (or Not) but it's worth a try.

Very nice series. Good job!

Outstanding series. Great photography. Thanks for posting.

No worries.

You made the assumption that I used the R-200s mounted on the front of the lens for stacking but I don't. They are mounted OFF camera on articulating arms & were triggered by the pop-up flash. Since I had problems with the camera overheating while using the pop-up flash in commander mode, I now use my SB-800 in commander mode to trigger the R-200s. I use the Watson rechargeable CR123A batteries in the R-200s & can get over 200 flashes @ 1/2 power & 300-400 flashes @ lower power settings.

You will hear a lot of negative comments on the Nikon R1 (Close-up) Speedlight system. The main negative comment being that it is under powered. I have one & really like it for field work. The camera's pop-up flash, as you probably already know, can be used in commander mode to trigger the SB-R200 flash units, which works perfectly. But, if you plan to also use it for studio focus stacking, you might consider the R1C1 kit which includes the SU-800 commander unit. The reason being that if you shoot over 45-50 images on a deep stack, the camera overheats & shuts down the camera's pop-up flash. With your automated rail, you'll end up with a lot of black frames as the stacking controller doesn't know the flash quit working. As you have said, lots of things to think about.

Super series. Very nice variety.

Very nice stack!

I'm not an engineer, but I would say no to the goose neck. With the weight of the lens already pushing down on the top front bushings & lifting up on the rear one's, I would think the goose neck would act as a lever & multiply this pressure. Please correct me if I'm wrong.

I'm assuming that you will be doing stacking in the field. This is a very good post with equipment photos near the very end. Hope this helps.
http://www.uglyhedgehog.com/t-258435-1.html

Thanks to everyone for looking & commenting.

Very nice series. I like to study the enlarged downloads. Very interesting subjects. Did you notice the little critter on the stem of the thorn? (Upper right side) Well done.

He thought he was going to spend the winter in my house. Hummm, come to think of it, I guess he will. Focus-Stack of 72 separate, 1:1 images, captured with a Tamron SP 180 macro.

(Download)

Great series. The last one is very interesting. I've never seen one of those.

Super shots! I really like the 1st one. You caught it cleaning it's foot.