Not to pick sides I see both points of view. If someone asked me, and I've answered on here before. I feel most people will be safe on 27, the more aggressive and heavier the tire you get to higher there likelihood of a problem.
With that said, they have people that tear up machines on 25in tires and people that ride 30in and never really have an issue. The best we can do is speak in generality because we all drive differently in different environments.
I run 28, ran them on the grizzly never had a problem on it.. When I really get suck, I get pulled or winched out.. That's when things get in a bind and break. I'm more likely to put less stress on the machine by not getting stuck as often as someone on a stock machine, but I drive tactically, I pick the best lines and lock 4wd, or the front diff before I get stuck.
I will say this for me is a hobby, I ride for fun. I don't use my wolverine for work.. I accept things no matter how well built will wear and /or break.
I'd say do exactly what you're doing. Asking questions and research. Build what you want and ride it within its limits and you'll have years of fun on this machine.