you are thinking of training.

For a reserve line, they essentially create a custom R line for you with the appropriate number of days.

In your case, they will build an R line w/11 days on it trying to keep any R day blocks your existing R line had in it.....with you being able to make some requests. (If you expand, you will be responsible for fewer R days).

The 48 hour buffers just give you more continuous time off....e.g. get 2-13August blocked free versus 4-11. Still have to serve all of the remaining R days. So, if you just want the time off and not specific days off, I'd expand my vacation and waive the buffers. If you want specific days off, then I'd slide my vacation left/right, expand it of course, and keep the buffers.
(The bid period processing window will give you a graphical representation of what you've requested)

In your case, since you want to fly. You can request to be converted to a secondary line.....but, given that there is so little flying available, I'm thinking it's unlikely that you will be converted.