Julie,
In general, the trailers are simple, but the thought processes that are required to get all those simple pieces to fit together are not.
Most folks go through up and down stages while constructing a trailer, or other big (that takes more than a weekend or two) project.
After the excitement of discovering they are able to install the floor and sides in just a day or two, one begins to get a false sense of the true time line.
It is easy to "dream big" and begin to think that "this project is really going to fly".
Parts of such a project do, though many parts do not.
While one day you might check several items off your to-do list, the next may be spent doing nothing more than trying to think a problem through, or doing some minor chore that turns out to blow the whole day (trashing your schedule and leaving you feeling like you've failed).
But you have not failed, you have just gained a better understanding of the process, and are now better equipped to deal with the next...opportunity
As Doug and others pointed out, in the end, done right, it is all worth it
Rob
Waiting for "someday" will leave you on your deathbed wondering why you didn't just rearrange your priorities and enjoy the time you had, instead of waiting for a "better" time to come along...