I've seen the All-in-Ones in several apartments of friends, children even grandchildren - and almost no one is happy with them.
Now, I know they come in different versions. The models I see in RV parks seem to be larger and heavier built than the apartment ones.
I see on the Lowe's web site that GE & Frigidaire make a 3.2 cu ft Washer/5.9 cu ft Dryer model - while Whirlpool makes a 1.5 cu ft Washer/3.4 cu ft Dryer combo.
The smaller unit certainly isn't built to withstand as much as the larger unit.
Another question - how is the dryer mounted? In an RV it is going to be subject to much higher stress on the mounting as the rig goes down the road.