I believe that salesman is trying to upsale you. uninformed people assume 5vers are better because they are generally more expensive. You do have to compare trailers fairly though. There are more 'starter" TT's available usually, but you can find a TT that is just as well appointed as a 5ver. Personally my TT is much nicer than a friend of mines 5ver and also the Class C my parents had. Granted it is not an entry level TT but one that is a step up.
I travel solo and use the "backup balls" like 2012 Coleman mentioned. As others have said an electric tongue jack is essential. I have a rear view camera mounted on rear of trailer that helps when I back up. I really feel more comfortable with the lower height of the TT when towing. I don't have to worry quite so much about overhead limbs while I am parking.
I have found pull-thru sites or sites that are easy to get into are available most places I want to go.. or maybe I just pay attention to site layout, when I make reservations or pick sites.
As a solo traveler, I have found I don't need a huge trailer.. I have a 28' total length trailer.. a Jayco 24RKS, it has room for me to do anything, and if someone (like my DS) decides to join me they can sleep on the sofa. I picked the floorplan for ME, not for lots of other folks. I plan to go fulltime in a few years and I still plan to stick with a TT that is only slightly larger than what I have now.