it is a PITA to put a T in existing. basically ya you got to hammer out a bunch. BUT, you can get rubber pipe couplings that are sealed with hose clamps. It doesnt need to be the regular PVC joints. So with the rubber couplings on either end, you cut out a section, slide the couplings on either end, set back in place and slide couplings up over the pipe. Not as bad as you think
these are what I'm talking about
