First of all, you are mixing, not mastering at this stage. Make a fine balance, dynamics and all and keep your peaks away from the peg. If you have to crank your monitors to find the average feel, do so..even though peaks may be too loud, this is the "good stuff".
A little bit of channel compression on certain instruments can help you if it stays very musical. What is kind of habitual with me on large mixes is to get the subgroups going to give you some bussing control. What if you have to do some minor gain riding in automation? Great!
I really feel that their is some confusion on the part of mixes being compared to final consumer ready product. You can lean on your mastering engineer (that you trust) to settle the "professional format to consumer format issues". If you are going to attend the mastering session, it does not hurt to burn yourself a one off of some 2 buss compression for comparision sakes. Compression does change balance, so EQ is part of restoring that balance. Listen to that and see how it feels. Your mastering engineer will certainly get everything consumer equipment friendly, that is their job.