Pushing the limits of a 5 or 10A reg in a confined space is really dancing on the minefield.
A modern 2M Pattern application does not have to be that big of a problem for a linear regulator to run cool, even if adding a CDI power draw into the mix. I'll say this much, there were many consious thermal design decisions involved in the ratings, shape and placement of things on the PLR5. My friends and I fly what I make, and let's just say that I don't want to let any of us down.