Currently you cannot chain proxies to Tamper. I will add this to my to do list. If this helps, know that Tamper sets Chrome proxy settings to go through its pr

Currently you cannot chain proxies to Tamper. I will add this to my to do list. If this helps, know that Tamper sets Chrome proxy settings to go through its proxy using a PAC file. You can modify that PAC file by clicking the little cog icon in Tamper.