Several folks have looked at these, and I considered a mini split system myself due to Seer rating and noise. However, the benefit of a roof top unit is that it doesn't take up room in a trailer where space is a premium. Additionally, from an efficiency standpoint, you're starting cold area at the ceiling. It falls from there. If you put your ac in the floor, your head is hot and your feet are cold, which feels uncomfortable. However, the Thor system you show looks like a forced air ducted system, so you could use PVC pipe to get it up into the ceiling or near it.
I struggled for a long time before I decided to put a unit up top. I was going to try the old window unit in either the front or back window, but in the end didn't want one end of the trailer freezing, and the other not, and have to keep moving a portable around.