Great question! If buying from a dealer, most offer a dealer warranty/ maintenance package...at extra cost. That might be your only option. A new Hi-Lo should be problem free, but there have been a (very) few new trailer issues brought up in this forum, so having a warranty may be prudent if it puts you at ease about this purchase.
An issue that came up several times, with the 2010 models, involved a lack of clearance betwen the propane tank cover and the front window, and subsequent rubbing damage to the window. I don't know if this was common to all 2010's of that model, or unique to just a few. In either case you may want to do a search and check out that thread. The only other new trailer issues I remember (although there could be others) reading about were a plugged drain line... some sort of manufacturing debris lodged in the pipe, and an axle mis-allignment... a really rare problem that caused a quite interesting discussion thread.
1967 17' Hi-Lo Bon Voyage (1967-1969)
1969 19' Hi-Lo Bon Voyage (1969-2011)
2004 27' Hi-Lo TowLite (2010-present)
2015 Chevy Tahoe LTZ