I'd expect that v5's three columns (MAC|IP|hostname) would be enough for the vast majority of v6 users as well, especially since that would be what they did configure in v5.
If v5 users needed some of the more exotic options, they probably have created a custom dnmasq conf or edited the file directly, so they'd be already somewhat familiar with dnsmasq's detailed options.
Instead of trying to fit all possible options into a table, how about making the existing table a Basic level interface, with a new, extra column 'expert options present' that shows as ticked when more options are set, and replacing that with the current v6 style view in the Expert panel?
Parsing the Expert options for the Basic UI shouldn't be overly difficult:
Strip or ignore options starting with set: or tag: as well as ignore, and then parse by strict order, the first being MAC or id, second IP, third hostname.
Sorting Basic should affect how Expert lines are sorted accordingly.