If the trailer axles get too far apart, it is no longer a trailer, it becomes a "wagon." But yes, the greater the distance the axles the more stable the trailer becomes when towing. But.... when turning to back up, the side resistance on the tires (because they do not want to pivot on a single point) can reek havoc on the tires. That's why some tires are rated for trailers and other tires are rated for automobiles. Track better ... yes. Pivot in a turn... worse.
(that's why "wagons" have a front axle that pivots).