Fascinating but impractical. Rome is on the Tyrrhenian, Venice on the Adriatic. You’d need to play seafarers (unless you plan to build a canal). Anything’s possible, but honestly the idea is time-consuming and not really an effective way of “living” Italy. You’d be mostly on water, with only the Rome-coast inland trip. If you want to sail, stick to one side of the country. But bottom line, rethink.