The 300 in stock form would be lucky to handle a 26" mud tire well in any real mud, let alone a 28" tire, and something as heavy as the OL2. You'd want a GR for sure. They make 30% now and that MIGHT cut it for OL2's but 54% would really be safer. OG laws are a bit shorter and lighter so you could probably get away with the 30% with those.
Fitting 28's isn't a big deal. I always run steel floorboards on mine, with about a 1.5-2" lift and the fenders zip tied to the floorboards they should fit no problem.
I agree with 26's being the cut off point for a stock 300 , my 300 spins 26x12 rear and 10 front Mudzilla's no problem , but I do have a cam and CDI in it , my other 300 has 27 Swamp Lites on it right now but it has a 54% reduction , I am going up to something around 30's on it and Outlaw 2's are my first choice
like Mac said about floor boards and tying the fenders up , add a 2 inch lift kit you can put 27's and made 28's under it , but it is going to choke it down hard