There is a solution to this issue in 2.2.3-13 and 2.3.1-17.
Sail now references a set of include files when it generates the major .conf files. They are called....
sark_customer_iax_devices.conf
sark_customer_iax_headers.conf
sark_customer_iax_registrations.conf
sark_customer_sip_devices.conf
sark_customer_sip_headers.conf
sark_customer_sip_registrations.conf
sark_customer_manager.conf
sark_customer_queues.conf
You can edit these files from the general edit panel and you can put anything you want into them.
They will survive sark release updates. The empty files will be created the first time you issue a commit from globals after you have installed the relevant release.
Using these include files, together with custom-apps, SARK/Sail is now completely open in that you can add your own trunks, extensions and extensions.conf code
completely outside of SARK/Sail control if that's what you want to do.
docs page is here.
http://sarkpbx.com/twiki/bin/view/Main/DocChapter2525Best
S