Ya if that's the case i would recommend The Pearl Street Bar and Grill, or as previously mentioned some of the bars right near the HSBC arena. (Pearl street is about 3 or 4 blocks away, some other bars already mentioned are closer)
would also recommend to show up tailgating early in the 8am time area just to take in the full scene and not feel rushed.
off the top of my head most often have problems with fans from cocky teams or rivals that we play a lot ex (jets/dolphins/pats/steelers/raiders etc..) not often i've really seen random fans from non rival teams just minding their own business getting confronted or anything. it's usually the obnoxious pats or jets fan trying to egg people on that doesn't end well. I can't imagine problems with Lions fans, if anything we can sypathize with you guys.