"Is this sufficient insulation for the trailer."
Short answer: No.
You can never have "sufficient" insulation anywhere, not even in a house. But in a 2 inch wall, that's about all you are ever going to get.
Every RV owner, regardless of type of RV, deals with heat and cold, and every one of us has different ways of dealing with it. Some RV come equipped with 2 air conditioners. If the camper was 100 percent insulated, it could easily get by with only 1. But because of the thin walls, insulation can go only so far. For those who have only 1 air conditioner, if the air conditioner cannot keep up, owners will often swap out for a beefier air conditioner, or add a second one themselves. There is a point where even the best of campers are never insulated enough. It cost to cool them. There's no way around that. Even if you rely on solar power, you have the cost of the solar equipment to get the electricity to power them.
Same is true in winter. Read these forums and you'll see those that winter camp always have insufficient heat. One would think with a 100% insulated camper, a simple space heater would roast the inside when the outside temperature is 50 below zero. But in an RV, they just aren't insulated that way. Winter campers are always struggling for additional heat, supplemental electric heaters, looking for ways to boost the heat from their furnaces, skirting under their campers, sealing cracks, replacing windows with double pane windows, all sorts of things. WHY? Because 2 inches can only insulate so much, and it's NEVER sufficient.
For what you are describing about your new camper, you'rs is very, very typical of any RV. As someone else above said, "It is what it is." That is so true. Without massive modifications, you can expect the air conditioner to work hard in the Summer in Southern Texas or Southern Florida, and your furnace to be complete inadequate in Alaska in the winter!
But, we all adjust. It is, what it is.