Sorry for the unregistered comment, but this forum discussion was the highest return on googole for "are motorhomes safe," and I was a little frustrated by the preachy (forgive me) responses with no effort to provide actual data. I did eventually find an informal analysis by a grad student of motorhome traffic deaths reported in the national highway safety database.
The forum discussion is at
http://www.rvforum.net/SMF_forum/index.php?topic=20505.0
Here are the conclusions:
Summary:
The revised FARS analysis shows that a total of 212 individuals perished in motorhome accidents in the years 2000-2007 for an average of just over 26 fatalities per year. This represents an average rate of fatality of 0.44 per 100 Million Vehicle Miles vs. 1.48 for all vehicles in the United States, or roughly one third the average rate of all motor vehicles. (See Chart "Fatality Mileage Normalization Chart")
Observations:
1) The "Initial Harmful Event" which is the event deemed to have caused the crash, was overwhelmingly due to striking another vehicle in "your" roadway (45%). That can mean a vehicle traveling the same direction of a divided highway, or a vehicle traveling in either direction of an undivided road. Vehicle Roll-over, Striking a Guard Rail, and Striking a Tree, each represented approximately 9% of total crashes respectively. (See Chart "Initial Harmful Event")
2) The majority of fatalities occurred in the front seats of the motorhome, with 80% being either the driver or passenger. Of the 26 rear compartment fatalities, only 2 persons died while using a restraint (seat belt). No children using child safety seats died during the analysis period. (See Chart "Fatalities by Seating Position and Restraint Usage).
3) Alcohol did not appear to be a significant contributor to motorhome fatalities. (Less than 1% reported drinking as a factor)
4) The majority of fatalities occurred on rural interstates and/or major rural highways (54%). (See Chart "Road Type")
5) Trailers of any type were only reported in 26 of 212 fatalities during the study period. Of those, only 3 were reported as towed vehicles, however that statistic was only added to the database in 2005 and is therefore statistically irrelevant. (See Chart "Fatality by Reported Trailer Use")
Conclusion:
It is difficult to come to any supportable conclusions about accident causation, however, what it is clear that motorhomes are statistically very safe relative to the overall vehicular population. What limited fatal crashes do occur appear to be largely caused by striking other vehicles and fixed objects near the roadway and the resulting fatalities seem to most often occur in the front seat. Given that there were only 26 reported deaths of individuals in the rear area and only 2 of those were belted, one can draw their own conclusion about the merits of using a belt.