Twenty miles can be straightforward. It can also mean narrow lanes, summer traffic and a last bus home that leaves before the date has properly started. Matching here is weighted by realistic drive time on Cornish roads, not just straight-line distance.
That matters because Cornwall is long, and its transport links tend to run east to west rather than conveniently between every pair of towns. Someone in Falmouth may find Truro easier than a village that appears closer on the map. A match between Penzance and St Austell might be perfectly workable for two drivers, but a nuisance if one person relies on public transport.
A useful local match is not simply nearby. It is someone you can realistically see again next week.
Use your profile to make the practical side clear without publishing your full address. Name the town or broad area where you spend most of your time, say whether you drive, and mention if you are open to meeting halfway. If your working week moves between places, include that too. Someone living near Wadebridge but working in Bodmin may have a wider practical radius than their home postcode suggests.