hey guys, I am looking into getting a travel trailer, and was wondering if there were any brands to avoid? my budget will only allow up into the late 80s/early 90s. I want a quality unit, and would pay a little more to get quality. are trailers out of the 70s any better build quality than newer ones? also, a quick dumb rv question: how often does the roof need re-sealed, and is an Airstream or spartan aluminum skinned trailer exempt from this maintenance ritual? thanks guys!