Adding data to a live DVD+RW

Here I am with a live DVD+RW that has Trisquel 7 on it. It boots into the trial/live version of Trisquel 7 just fine, but there is some sort of obstacle to adding data, such as the clone of a website of mine that I'd like to distribute along with the means (i.e., Trisquel) to browse that website clone without the limitations of Windows.

I see /rofs which has 1.5GB of space, presumably for the permanent addition of other Trisquel applications to flesh out the Trisquel live installation, but my website clone requires 1.9GB of storage space.

Brasero only wants to blank the DVD+RW disk when I try to add the 1.9GB website clone, as does CD/DVD Creator. The Trisquel live DVD+RW is mounted as a read-only file system.

All I can conceive of attempting is to convert the website clone into an ISO image and then combine that image with the Trisquel ISP image that one downloads in order to create the live DVD. Once I do that, will the result be a live DVD of Trisquel plus my website clone in a directory that I can access when I run the live Trisquel installation ?