FIR filter with relaxed transition band
Instead of using the FilterDesigner Tool consider using the firls() and firpm() commands directly since they will return optimized filters (in the least squares sense or peak error /equiripple sense respectively) very easily with one MATLAB command. Type help firls or help firpm in MATLAB to read further documentation on how to use these and specifically how the parameters define the transition bandwidth desired.
This can equally be done through the FilterDesigner but I see no need for that added complexity.