We had carried a brand new Shadow 300 for two years, then tried it out on our Triton last year and used only that for the rest of the season! They are so good. I did adapt mine to have three vertical poles (adding a big eyelet in the orange triangle on the main panel), but that extra cover would be great on our new-to-us 2016 Troll 540 that's coming soon to our household (don't tell Poppy our Triton as she doesn't know yet...)
It looks like a 360 would be perfect, really. I just saw a very good secondhand 400 going relatively cheap online. I'll keep the 300 for the other side of the caravan in hot weather.