Yep, using a bucket or splitting the batch are probably your best options. Although a larger-diameter blow-off tube isn't a bad plan, at least it won't clog with fruit chunks the way a small airlock pipe will.
And you don't need to worry about headspace when your mead's in a foll-on fermentation stage, but once you rack to secondary you should make sure it's up to the neck so you don't have oxidation problems.
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