My rear brake feels neither mushy nor non-existent. It's not nearly as powerful as the front, obviously, but I can feel it when it kicks in. Two things to check/do: inspect the brake lines. Rubber lines degrade and lose pressure over time and it's the pressure in the system that engages the pads. If you didn't replace the all the fluid in the rear circuit when you replaced the pads, try that first. Buy a new, sealed container of fluid when you do it. Brake fluid degrades over time and sometimes just replacing all the fluid does the trick. If new fluid doesn't take care of it, put a braided stainless brake line on and see if that helps.
An adventure is an inconvenience rightly considered. An inconvenience is an adventure wrongly considered.