iax2 extension trustrpid

Whenever an iax2 extension is created under the extensions module, it adds the following in to iax_additional.conf:

callerid=FSPBXIAX <80000>

Is there a setting somewhere within FreePBX that will allow me to force it to put trustrpid=yes and sendrpid=yes in there instead of the above? I am using IAX registration to nail open the IAX2 tunnel behind a NAT device by specifying host=dynamic on the remote end. However, I’d like to be able to pass the rpid through the IAX2 trunk. I can do so by manually removing the two specified lines and putting the others in, but this is a pain. Usage of the iax_custom’s will result in the inability to choose the extension within FreePBX as a destination, which would mean I would have to use the custom extension config files to set destinations on them. I’m hoping someone already knows of a workaround/setting to change this behavior?