The OP hasn't replied yet, but the only Safari FRED's I can think of is the Trek. The larger Safari coaches are pushers with large Cat or Cummins.
They will be like countless Bluebird (and other) FRED school buses - there's only so much you can do to quiet down the rattling underneath your feet. They're reliable depending on what diesel is used, but not quiet nevertheless.
If you're going to hop scotch from campsite to campsite, it's probably livable enough, and the MPG will be better than a gas rig. The DP's are nice for long trips as noise does wear you out after a while, and there's little in a DP. (Like riding in your home's living room) High noise does cause fatigue.
FMCA# F355513. 40 foot Safari Continental, one slide, Cat powered Magnum Blue Max chassis, PAC brake PRXB, Allison MD3060, Aqua-Hot, 7.5 KW Quiet Diesel, Howard PCS, Velvet Ride suspension. 2006 Jeep Commander.
I have a 98 Newmar Mountain Aire 37 foot FRED, I have 100,000 miles and have had no problem with this engine, The noise is not bad and it get 10+ MPG pulling my full size pickup. Just went to California and it work just fine in the mountains, I did put the Bank system on 8 years ago, it work just fine for me and is easy to work on.
No more noise than a gas engine and there is no smell, in fact when it warm up it sound just like a sewing machine, no noise. wife and I talk normal and listen to the radio, and I can change the oil, grease and change all filters my self, cost about $25.00 to change oil and filter, not $300.00. I had it for 15 years now, brought it new, it a 98 Newman Mountain Aire 37 foot, Cummin 210 HP engine, with a Bank System now, make it about 300HP. IT'S FRED.