I've struggled to find opponents on the servers recently but I've had some fantastic games with just 1 or two opponents. The problem is that a lot of the maps are just way too big for such games and you end up spending most of the time hunting for your opponent or blowing up dynamite to let them find you.
Some of the duel mode mini maps would actually be superb for small games, not the really basic ones obviously but the more interesting maps with a building or two or the one with the church. Also there are parts of other maps which would work well in a cut down form too, the big house from Tillian, half (either one) of backwater etc.
Does someone with a bit of time and talent fancy doing some conversion work? (I have neither)
A mode like the 1 vs 1 queuing system as used in Open Arena would be fun as well. Winner stays on of course.