A fifty-mile radius sounds reasonable until it crosses the Great Glen, puts water between two people or turns a weekday coffee into most of an evening. The Highlands cannot be treated like a city with the population spread evenly around it.
Inverness and the Moray Firth have the largest concentration of people, so members there may have several practical options nearby. Around Ullapool, Lochinver, Portree, Fort William, Thurso or the smaller glens, the pool will naturally be thinner. That is not something an honest Highlands dating site should hide.
A smaller pool within a manageable journey is more useful than hundreds of profiles you will never realistically visit.
We give weight to how people actually travel. A match along the A96 may be simpler than someone apparently closer across awkward roads. Skye, Wester Ross and Lochaber each have their own travel patterns; Caithness and Sutherland are not interchangeable just because both are in the north.
Your own limit matters too. For one person, forty minutes is ordinary. For someone working split shifts in hospitality, covering NHS rotas or starting early on a croft, it may rule out meeting during the week. Be clear about that from the start. It saves both people time without making either of them seem unwilling.