Mirrors, bigger and wider are always better to see around the trailer, small car mirrors often do not stick out far enough or are large enough to get a view of what is going on beside or behind you. Many motorists love to drive beside you in your blind spots or hug your trailer bumper, better mirrors reduce the blind spots. So unless you love to drive blindfolded some towing mirrors will be in your future.
Very few Travel trailers are built with built in generators, trailer small enough for SUVs most definitely will not have a built in gen or even an option for a built in gen. You will need to buy your own portable gen.
CONVERTER which charges the 12V battery on the trailer and supplies 12V to the trailer while plugged into a gen or commercial power is standard built in item with modern RVs.
INVERTER which takes 12V from your trailer battery and creates 120V AC is not standard or included as an option on most Travel Trailers. If you want that, you will need to install yourself and most likely will need to upgrade the small trailer battery to a bigger battery bank setup depending on what you are planning to power.
Toilet on all but the smallest hard sided travel trailers will typically be a standard RV flush toilet with black water holding tank. Extremely small travel trailers may not have a toilet at all (Think Canned ham trailers like TAB). Not sure if many trailers are equipped with standalone cassette toilets, might see those on Popup trailers.
Very small trailers the manufacturers typically will not recommend WD and your SUV may not have a hitch designed to handle WD.
As far as friction "anti sway" devices goes, that will depend on the manufacturer recommendation and the type of hitch head you end up with, some hitch heads and trailer tongues cannot be adapted to have friction anti sway devices.
Small RVs often will have very small manual RV fridges that will require you to manually light and when shore power is available you will have to manually switch over to shore power.
You do not want a fridge to depend on your car alternator or car battery, typically RV fridges with auto change over will have a control board powered by the trailer battery. Manual change over fridges typically will not have a 12V control board.