The guy you saw standing there looking at his trailer probably doesn't know how to change a tire otherwise he'd be on his knees!!
But to answer your question I keep my 4 way lug wrench in the TT. My TV has a nice scissor jack that it came with from the factory and will work nicely on the trailer. Wheel chocks are in the trailer. If I need blocking there is firewood. If I'm on soft earth I can use one of my Lego leveling blocks to keep the jack from sinking in the soil. Use your head, improvise, adapt, and overcome!!
2006 23B Hybrid with 10k round bar WDH
2011 F150 4x4 SCREW Ecoboost, Max Tow, Integrated TBC, 3.73 LS axle, Firestone Ride Rite airbags.