Recording at a lower level digitally is a very good idea. Many are still pushing things way too loud and wonder why they get into trouble. At 24 bit recording even in the real world, 138 dB of dynamic range is still possible. So even if you are at -20 (or -23) you still have 118 dB of dynamic range under your belt!
If you use a decent VU meter plugin
(such as the Klanghelm) all this is much easier too. You can choose a reference that the meter will show 0dB VU. I tend to work with the K system and work with either K-14 or K-20. You can use VU meters on tracks, buses and the main stereo buss too. This way you don't need to consult the loudness meter until the mastering stage. If you VU meter everywhere especially before and after plugins and plugin chains you will never bring on a clip light anywhere, ever.
(and you will never clip internally with any plugin either) There is no need to be up near 0 dB FS ever.
When you do this all your mixes will all be at the same level prior to mastering.
Mastering up to -16.5 or -15 is also a good idea because that seems to be the level that the iTunes sound check feature works at. iTunes won’t change a thing eg add or subtract gain at this mastered level leaving your track perfectly intact.
I have had some mastering clients though that would not accept this (-15) either and they would say it is too soft. You can go as high as -10 to satisfy that and the mix will still sound punchy and transient but louder. The trick is to also use a DR meter (dynamic range) and keep an eye on the dynamic range before and after mastering and it will stop you from slamming tracks too hard and making them sound bad.
I work with three metering systems now. VU meters during the production and the DR and Loudness meters in mastering. The loudness meter is very interesting too.
The other aspect of VU metering which people just don't get or want to is the movement of the needle or ballistics. When the meter swings wildly either on a track, buss or main mix it means there is something wrong. You can track it down and fix it and it is usually only one or two things causing it. When you set up a compressor correctly the meter moves in a certain way and when it is not set well it moves in a different way. This information is just not available with any current peak metering or even rms metering system (bar graph displays are not where it at) used in most DAW's. DR and loudness meters wont help you either in this area too.
When everything is right in the mix the meter just dances beautifully right up to 0 dB VU and rarely overshoots much and rarely jumps over wildly. That is when the mix actually sounds the best. You can even mix with a VU meter bringing in things one at a time and allowing for the needle to start lower and eventually when everything is in, it is just hitting 0 dB VU. I have expensive real VU's and they still have the edge but the Klanghelm VU is very good though and does the job.