Don't worry about the single axle, just keep good tires on it, and check them often and you will be OK. I would second the choice of 16 inch tires instead of the 15 inch ones if they will fit. We changed them on our 20' Safari and really like them. More tire choices and a little bit more clearance. Also, if you like the 20' Safari, keep your eyes out for a good used one. We found ours in Florida on Craigslist and traveled 1500
miles to get it, but it was in practically brand new condition. We purchased it for less than a new Sport, and we love it. My wife and I think that it is the perfect size for our travels, is easy to tow, and has all of the space that we need. There are some good buys out there on used smaller trailers that are being replaced with larger units.