Yes SampleTank does require CC11 to be assigned to CC7 to have an approximate effect on the sound levels. I have tried, over a number of years associating CC11 with other parameters such as Velocity with little success.

I have found that it is difficult to mix a combination of tracks using CC11 associated with CC7 in the Midi Format, but if each track is recorded to audio then mixing is easier.

It is useful to create a Multi in ST which contains all the associations you would normally use as a Standard Set Up for each new project.