There are several issues that can affect steering.. Yes. it may be that adding the additional pressure will work..
The major issues with high pressure are as follows:
Tread Wear.. High pressure means the CENTER of the tread will wear faster than the edges. Normally on an RV they age out before they wear out so I'm not sure how much of a concern this is.
Handling: On less than optimum roads you have less than optimum traction. This COULD be a problem if you routinely drive on bad roads.
RIDE: harsher (not a factor)
And if you go TOO high.. You can over stress and blow up (As in BOOM) the tire, however so long as your clod pressure is LESS than the pressure molded in the side wall you should be good.
You might try 90 PSI
And it's also possible you figured the pressures wrong.