Although this tool is designed for bypassing SSRF filters, the techniques and tricks that the tool provides can come in handy when attempting to bypass redirect filters too: https://github.com/cujanovic/SSRF-Testing/blob/master/ip.py.
$ wget https://raw.githubusercontent.com/cujanovic/SSRF-Testing/master/ip.py
$ python ip.py 188.8.131.52 80 bugcrowd.com
Dotted hexadecimal IP Address of: http://184.108.40.206 + authentication prefix/bypass combo list
Also, some of the techniques used to exploit CORS misconfigurations described in https://www.corben.io/advanced-cors-techniques/ might help you bypass that whitelist.
That being said, if you notice that none of this works, it might be worth moving to something different and not wasting too much time. The whitelist could be designed in a way so that you can only redirect to a trusted host.