There are several things too watch for, but probably low over heads like gas stations and trees. Then the fact that a 5er does turn faster then a TT with obstacles "jumping" out at tires and the side. Pulling across drainage culverts can cause you to ding the trailer and bed of the truck if it's too abrupt. For the most part, if you can find a large and empty parking lot and practice turns and backing and doing it s-l-o-o-o-w-l-y your adaptation time will be a lot faster. The dealer took me for an orientation 'cruise' to a parking lot and worked with me for the best part of an hour when I purchased my first 5er.
If you have a long bed, not too many problems with rear window interference, but a short bed truck - you do need to be well aware that a 90* turn will probably not be possible (tho they are seldom encountered)
Just take your time - and welcome to the world of 5ers
Dave W along with my DW, Susan and our poodlepups, Callie & Molly,2011 Ford F250 6.7 CCLB, 5er Hitch Option w/B&W Hitch,,Ride Rite air bags, 2014 Montana High Country 343RL (38')