If you're looking for a meeting place or a good stop around ½ or halfway between Clifton and Mount Bethel, you can try Landing, NJ, which is about half an hour west of Clifton, or about half an hour east of Mount Bethel.
About ¼ or a fourth of the way, you can stop at Troy Hills, NJ. This is about 14 minutes west of Clifton.
About ⅓ or a third of the way, you can stop at Parsippany, NJ. This is about 18 minutes west of Clifton.
About ⅔ or two thirds of the way, you can stop at Waterloo, NJ. This is about half an hour west of Clifton, or about half an hour east of Mount Bethel.
About ¾ or three fourths of the way, you can stop at Southtown, NJ. This is almost an hour west of Clifton, or about 14 minutes east of Mount Bethel.
If you drive straight through without stopping at all, the total distance is 58 miles. The distances shown above don't include local roads to get into each town, so if you're planning a long road trip, make sure you factor in traffic and road conditions, rest stop breaks, and interesting detours along the way. If you're in a rush, you can do the trip with zero stops, and your total travel time would be around 58 minutes.