Hurth even says you can, though they don't recommend it as standard practice.

I though long and hard before putting the saildrive in my boat. I could find no epidemic of sunk boats due to the gland failing. But I sure don't like the alloy drive leg. It was fine in fresh water for 1.5 years. After 3 months in salt water the corrosion is already starting. One thing I did do is abandon the internal water intake (filled it with Pexus) so at least it isn't corroding from the inside out as well as the outside in. I think the ideal would be a bronze or SS drive leg that you bolt through the bottom of the boat, then hook up a standard in-line transmission via a CV joint. PYI used to advertise something like that, except rather than a bevel gear cardan shaft it was driven by silent block chain which was a little weird.