As others have stated, I went from expensive cooler to a fridge and happy I made the leap. Well worth it IMO. I took a Canyon Cooler (rotomolded, similar to the rest) on a 4 days camping trip to Tahoe last summer and by the time I calculated in the drive and the 4 nights I had to fill up ice twice. Temps were about 85F in August I believe. I did everything recommended, added enough ice, limited how much I opened/closed it, and sorted the food according to how much I'd consume. By the end of it I was trying to dig through refrozen ice, bust up the chucks, take out my food and then somehow organize it so that I can again access everything in a convenient manner and also be able to close the lid. Honestly I think even the expensive coolers 2 days maybe 3 max is good. Longer than that you'll want a fridge and even if you're just on a short trip the fridge is much nicer to have. If you can afford it and have the extra juice I say go for it.
Now my thoughts on fridges. IMO you have your top tier players like National Luna, Snowmaster, and Engel. Supreme build quality, durable, and sometimes has a fridge and freezer compartment. Expensive. Then you have ARB & Dometic. Good quality, plastic build, fridge OR freezer but not both. Cheaper but still expensive. I think most people go with this option. Then there is the brand and product that won Overland Journal's value award but people don't really talk about it that much, the Indel B. It's nearly half the the price of an ARB or Dometic. You can scoop these up for around $450 shipped sometimes from Truck Fridge. It performs better than ARB and Dometic. The knocks on it is that the exterior quality is cheaper plastic, reverse control panel, and lack of drain plug. Oh it's also kind of ugly. I solved two of those issues by purchasing a Waeco fridge jacket that protects & insulates the fridge and covers it up so I don't have to look at it. The cover looks really nice btw. I could care less about the features and exterior quality since internal it uses a very high quality Danfoss compressor, which is what counts the most. The jump in price to get an ARB or Dometic is not worth it IMO. With the Indel B you basically get a the better performing product at $300-400 less. Either get the Indel B or make the leap to the elite fridges like a National Luna, Snowmaster, or Engel.
In my experience, it was easier for me to jump into a $450 fridge than an $800 one. Now that I've had mine and know that I like having a fridge, If I were to ever look to upgrade I'd go the National Luna or Snowmaster with the dual compartments. Also looking at the space you have on your trailer I'd say you could easily fit a National Luna 52-55L Weekender or Snowmaster 56L Classic. Just saying