Not too large with the AAA. It will be done just like the AA that Match modded (I have too). 13mm will go right in the head, after boring it out.
I have used AAA Eneloops in P7 lights for 3-4 years. In fact I still have one. They work well and they last for about 10-15 minutes DD on a P7 C bin. I don't think it will be an issue with a 1000ma driver. They take much more than they are rated at, just like the Eneloop AA batts. It won't be a long lasting light, but it should still do 1/2 hour with a 1000ma driver (depending on how efficient the driver is and the resistance in the setup).
I certainly appreciate your offer and I am constantly amazed at the knowledge here. It really is very nice to recieve these ideas and it makes me think. If there's any problem with the driver setup, I will let you know and will try the one you suggested.
Thank you