If you Google TPMS or Tire Pressure Monitor System you will find numerous systems. I would suggest you make your own comparison sheet and check each system.
Initial cost for system with enough sensors for your RV and toad.
Length of warranty.
Cost of ownership for 5 years and assume one change of batteries on all the sensors.
Be sure to note if the batteries can be changed by you or if you must replace the sensor when the battery goes dead.
Cost to install if the sensor mounts to the wheel (similar to the sensor on your car). If sensor just screws on your current valve this cost is $0
With a 35' MH I assume you have bolt in valve stems. For some owners of smaller RVs they might find they have rubber stems and it is recommended that these be replaced with metal stems.
I have 15 posts with the key word TPMS. I am sure some will answer other questions you might have.
Retired Tire Design and Quality Engineer (40 years experience).
Retired Professional race car driver.
Retired Police Driving Instructor.
Member, FMCA Technical Advisory Committee
Delivered Tire Seminar for RV owners & two seminars on Genealogy at FMCA Bowling Green 2009, Madison 2011 and Indy 2012
I am scheduled to present two seminars on RV Tires & Three on Genealogy at Perry, GA in March
and possibly Redmond in 2014
See my blog www.RVTireSafety.com and subscribe if you want notice of new posts.