Splitting it is a good idea.I do small batch BIAB, so I wouldn know about stuck mashes with that much of mashing. I seem to think splitting it makes it easier in general .It can be messy,but it is what it is. I just think its less messy splitting it. Seems people are 50/50 about it anyway.Some people dont have problem with mashes some do. Maybe putting some irish moss or whirfloc at the end of the boil also will further help settle it out better,maybe even whirlpool if you rack your wort. I just dump and use a strainer.. Ive had one settle pretty nicely to pour to the fermenter, but still ended up with a good amout of trub sitting at the bottom of the fementer.