I am looking at travelling to Basel, Switzerland early next week (Tuesday). It would appear that hotels are very hard to come by at a reasonable price, so I am looking at staying in Mulhouse in nearby France. It seems that a taxi journey between there and the part of Basel I want to visit (in Swiss Basel) is only half an hour. However, how easy will I find it to get taxis across the border in either direction (potentially around 6am or 10pm)? Are there any immigration formalities at all, or does the Schengen zone mean we'll be able to cross freely? I vaguely remember customs posts from a previous visit. Is the same true of German Basel and Swiss Basel?
Update: even if there are no immigration formalities, will taxi companies be happy to cross the border?