St. Lucia, Svalbard
If I'd found any evidence of some system I could map rather than just "there's some roads", you'd be able to map those travels already.
I'm having another look.
Svalbard looks like the most you'd get is the road through Longyearbyen to the airport and a radar station. There's only 40km of roads in total, most of which are short little residential roads in the 4 villages (none of which are linked together), and that road is 20 of them (mostly unpaved). OSM labels it '400', but GMSV shows no number from what I can see (though it doesn't do the more major bit between airport and settlement).
St Lucia seems to classify its road network into 'primary', 'secondary' (and presumably a lower category), but no numbers and certainly no signs. See also Bermuda, Bahamas, British Virgin Islands, St Kitts & Nevis, Anguilla, Antigua & Barbuda, Montserrat, Dominica, St Vincent & the Grenadines and Grenada.