Microsoft Outlook is a powerful tool but it has lots and lots of limitations, and one of them is this. A large PST file can lead to easily corruption and I know you don't want that.
It can be frustrating whenever we split PST because most of the time if we require any mail on an urgent basis it becomes a task to find it. But losing all mails and finding nothing is worst than finding something.
Try to eliminate your purposeless mails, I would also suggest you try Stellar Splitter for Outlook, as it can help you to split PST based on Size, Date, Email ID, and Folders and It preserves the exact structure of original PST files. Which will make your work easier. Since when I used this tool, I have no fear of large size PST file.