Hello jrlund1006 and welcome,
If you put any Comcast Gateway (CG) in True Bridge Mode (TBM), ALL routing will be disabled with the only exception of passing your CG WAN DHCP address to any interconnected Secondary Router's WAN interface. This means that your Comcast Static IP will no longer work in TBM.
I recommend that you send Comcast_Jessie or Comcast_Michael a forum private message with your account number, networking requirements, etc. and ither of them should be able to discuss any detail, recommendations, and set you up accordingly.
Hope this helps you out.