Well, I just saw this. This would shift the CG back. I assume you will be using friction fit to hold motor then since it wouldn't fit a typical motor retainer. Also, when the rocket comes down, the extended motor would take the brunt of the fall and might damage the forward motor retention unless you were using tape as a thrust ring. Haven't done this. I have a 4" rocket with an interchangeable motor size system and because of that, I can only use my 5 grain reload and not my 6 as the 6 sticks out like your ? Just my thoughts as I haven't done it.
