Length of travel trailers

The length of the trailer as advertised should include the tongue so the 29" would include about 3~4 feet of trailer tongue. There are some all season travel trailers like Artic Fox and others that can be purchased with a thermal package that will have better insulation all around including the underbelly where water lines and holding tanks are located. Of course all of that adds to the cost. My wife and I have a 23' TT that we've used for the last six years. For the two of us it's fine so I think bumping yours up to 29' should give you plenty of space although what is considered adequate space is totally subjective. The best think to do is find some that interest you that you can travel to within a reasonable amount of time and check them out. Nothing beats seen the space in person.