I recommended an approach in my comment on DCOS-39093. Philipp expanded on this, suggesting we scale them proportionately:
...we could share the leftover space in between the growToFill columns based on their share of the space so for example if we have two columns which have the growToFill Property. One has a size of 300px and the other one has 100px and we do have a leftover of 100px. We could add 75px to the first column and 25px to the second instead of 50px to each...
The `<Column />` component has an option to grow it's width until the Table fills it's container