Hi, I guess the type of routes you want to use for RPL's will be short and you are unable to vary the route due to the RAD etc, these are the only ones worth using an RPL for. To be honest I would leave your filing to on the day, this way you can guarantee what is filed is what is in the drivers hand. With the monthly AIRAC cycle changes, managing the RPL's will become a ball ache because not only will you have to keep your route database updated you will create more work with updating your RPL's too. The only benefit for RPL's is if you have a systems / communications error and cant file, at least you will have a plan in the CFMU system. As for adding a tail number I suppose the easiest way will be by sending a CHG message ?
All the best ML