I love memory foam, but on its own it doesn't make the most comfortable cushions. They tend to completely "crush" under a sitting person's weight
. If you lie down the larger area tends to reduce that problem. I used 2" memory foam on top of 1" high density foam in my Northern Lite
trailer, which should be a good compromise, I hope (we'll find out as soon as the snow is gone from our favorite campsites).
One other "issue" you should be aware of is that memory foam doesn't like low temperatures. If your trailer is at 5c or so, expect the foam to be as hard as a rock until it warms up
....I found that out by leaving my bedroom window open in the winter. Went to bed and it was like cement until it warmed up...