I think I just figured out a way to do this that will print the effect onto the clip in place... but I'm not 100% sure if it will follow any envelopes on the track.
If you select a track or clip, go to the global Process menu (at the top of the Sonar scree) and select Apply Effect it allows you to print any effects in the track's effect bin right onto the selected clip(s). So if you just wanted volume you could use any of the methods described in this thread to create a volume envelope using a plugin effect or FX Chain. Then use the Apply Effect option to print the it. You would want to disable any other effects in the bin you don't want to be included in the render (then turn them back on after). Since it's volume and effects tend to react to volume changes you may want to pay close attention to your signal chain/order in which you do this.
I'm also unsure if Apply Effect will indeed include any envelope changes to that effect but IMO it SHOULD otherwise that would be a little annoying.
Just something to play around with.
Now that I've looked at that option I think I'd like to see this feature get a little bit of improvement. Like give more options right in the Apply Effect dialog and generally make it all more robust and user tweakable. It seems to be a reasonable workaround for the limitations/annoyances of the whole Bounce to Clip/Track stuff.
I would would much prefer an in place render option for tracks and clips where you can just right click on a clip or track, choose the elements you want printed (like Bounce to Track and Export does) and have the changes applied to the specific clip. I don't why I keep thinking we can already do this but I'm pretty sure it's because of the Process stuff (as in I've seen many of these in place renders happen but via the Process menu).
Anyway... I'm sure OP already has his solution but thought it was interesting and might give folks some stuff to play around with. I know I'll be keeping it in my bag of tricks now that I realize it can apply FX Bin stuff. It would be even better if it had an option to include PC and Track strip options (and whatever else might come into play)... and of course an option to include/exlclude any envelopes on the track or maybe even live automation (during an audible real time Apply Effect procedure).
Meh.