The club has 1010 rails in six-ft and eight-ft lengths.
There is a two-piece 1515 rail that is 12-ft assembled.
There will be some loss of length due to mounting in the stands and standoffs to keep the rockets up from the blast deflectors.
Adding rail buttons is a great project. The MARS club in Geneseo, NY requires that any rocket launched with an F or higher motor use rails. At NY Power 2017 I had to retrofit two of my rockets with 10/10 rail buttons at the field. Last year at a RIMRA launch I did a field modification for a young person's Leviathan because the launch lugs kept coming off.
There are several options on how to add rail buttons depending on the diameter of the the rocket and a few other factors.
The below link is a video I created last year for a young rocketeer. In the video I use a 7/64 bit but since then I have found that the smaller 3/32 bit works just as well if not better.
Here is a professionally produced video.