Don't even think about a trip like that with iffy tires.
A blowout could endanger you and other drivers near you. Majority of blowouts on RVs are due to:
Overloading
Improper Inflation
Tire Age
Tire Condition (cracks, worn tread, unusual wear...etc)
Road Hazards
I've read where a blowout has caused the trailer and tow vehicle to rollover. Others have had significant damage to the trailer from tread impacting the bottom and sides of the trailer while trying to slowdown and stop. One RV'er caused damage to the vehicle behind when a piece of the blown tire impacted and broke through the windshield, luckily no one was hurt.