Thanks again for the responses. I was only clipping by about +0.9 on my master output meter, but got the impression that the ME wanted more headroom than simply ensuring that the peaks did not clip, and was looking for peaks in the -4 to 5 range. But, I am getting the feedback indirectly through the band member overseeing the mixing and mastering.
I obviously have some work to do to understand the appropriate levels for mastering. Actually, I have A LOT to do to understand it all.
Since this is my first mix for mastering, I hope to learn from the process. I also went back and watched the loudness meter tutorial again. In the end, I produced two mixes, one with the master buss fader down to where peaks were hitting -4.5 or so, and one where I left the stereo buss at 0 and reduced the pre gain on all of the channels/groups/FX feeding the master bus by the same amount. Most of the tracks were sent to groups and I had very little processing on the groups, so I could make minor tweaks and not have to worry about redoing my automation. I liked the second one better (master at 0), so that is what I sent off.
Hopefully I won’t drive the ME nuts and he will tolerate a newbie (and provide feedback?).