Regarding QGCS License

We are customizing the QGCS UI like changing the Logo, theme, App Name etc. for our commercial purpose without modifying any functionality of QGCS. Whether, GPLV3 is enough to distribute the software without publishing the source code or commercial qt license is required? If required, what is the procedure to obtain a license?
So, please clarify the terms of license to distribute the custom QGCS commercially.