Trailer size question.

[mushman]

I have an undersized single axle trailer now, I only use it to drop it in and pull it out.Trailer is 100 ft from ramp, so it's not really hitting the road, but it need some work, and if I ever needed to take the boat somewhere I really wouldn't feel secure about doing it.
I have the opportunity to get a tandem axle trailer, the guy says it will fit a boat up to 24'.
Would this be to large?, I'm going to go take a look tomorrow, anything I should look for, or measure to figure if it will be to big?.