Zippy 4S in a 3906 chassis

[JThiessen]

My B'in Law got a pair of Zippy 4S, and from what I can see from the specs they are going to be too big for his stock battery trays. I looked through this thread to see what people have done to accomodate larger batteries on this chassis, but found nothing other than going with an aftermarket chassis. THis is NOT an option for him, as his wife is already about to pull out the testicular bander (anyone who has worked cattle will know what this does).
I dont know yet if he intends to run two 4S in parrallel, or a single battery. The first thing he'll need is a set of G-Maxx Straps. Next, We have only two options as I see it. 1) add a filler block to the stock tray, and mount the battery "on top" of this. 2) cut off the outside plastic and either the rear or maybe the front vertical divider. Most likely would have to a piece of aluminum angle to protect the outside.

Anyone else do this type of mod for lipos on the old chassis? Thanks