Ok, well you (Jeff) asked !!!
01 - Extended Rail
These are custom by Ken Farrell Manufacturing, Warsaw, MO. They are 70175 Aluminum, I went with AL for weight. They are a wee bit "floppy" so I use a "red-neck-bedded" idea suggested by Aaron, a small amount of rubber cut to size (from my spare exercise mat) and gorilla glued to the front bottom of the rail. If the barrel moves up due to recoil, the rubber with compress a bit. The rail cannot flop down and touch the barrel, due to the rubber. This simple "r-n" idea seems to be working well, even on the .338LM. They are 20 inches long and that is a good length. If I had it to do over again I would add side rails as this would probably add enough strength to avoid any "flop". But these rails work for me, with the CO-LR on the .338LM or any other clipon on these bolt guns.
02 - Dual NODS
The better you can see, the faster you can go with confidence. If I am driving a vehicle containing others, with front glass, then the dual 14s are wonderful, that is their sweet spot. If I am out by myself and mostly on foot, then I don't find the weight to be worth the "see better". If it is really, really dark, then the 2 PVS-14s helps even on foot.
I am 100% glad I have 2 x PVS-14s though, as "two is one" and when one has to go to the unit depot, or even the main depot, I still have 1 x PVS-14 to use. And right now, one PVS-14 is in unit depot (at Aaron's) getting a new housing and I still have one PVS-14 on my helmet ready to go!
So, if you are a high frequency user (I average 3.5 night outings per week over 34 months) then I definitely recommend pairs of all critical gear. I have 2 x PVS-14, 2 x ir Clipon, 2 thermals.
Now, you said Dual NODS, not just dual 14s. So I also have a Q-14 helmet mountable monocular. I can mount it by itself on my other helmet using USGI mount. But goal is to mount side by side with PVS-14. This problem is equivalent problem to mounting a MUM-14 beside a PVS-14 and I guess not too many people need to do that - so I am a "one off" case. Aaron and Pete are both noodling the problem. I hope we can come up with a solution!
In the mean time, I can hold it up there, with left hand while riding on 4-wheeler and spot deer a few hundred yards away while in motion and that is the type of use case I had in mind. Ability to do hands free detection while moving. At the same time, I can use the pvs-14 on the other eye to see to drive. It works! But holding the q-14 up there is not convenient for driving and generates arm fatigue, so getting to the point of hands free will be useful.
On good thermal performance nights, I can roll with just the q-14 up there and keep a pvs-14 in a pouch for backup and that works fine. But on a poor thermal performance night I cannot see well enough to drive. I could still see critters in a sea of grey, but need the pvs-14 up there with the q-14 to be able to both see well enough to drive AND detect critters.
So a different sort of Dual NODS, which I think will definitely be worth it.
For basic foot navigation and hunting navigation on most nights, one PVS-14 on the head works fine.