I have 2-FF fans and 1-Maxair on my 5er and I prefer the Maxair cuz it's quieter and can work in rain. The Maxair is up from the stove and it makes the best range fan ever. One over the bed is great, too.
I had a 5er in the 90s w/o shocks and it rode lousy and bounced for a long time, at bumps. I didn't know at the time there were RV shock kits so I found 4 Monroe hd gas shocks that were meant for a pickup front end... they are shorter. I made my own brackets and those truck shocks did a MUCH better job than any RV shocks ever thought of. Tow your 5er for awhile and see what it needs. Craig