According to the only travel trailer manual I have, for a Silver Streak,
"The hitch ball on towing vehicle should be installed at a height of XX
inches to the top of the hitch ball when vehicle is unloaded. If it is
installed lower, tailwagging may occur."
Lower ball height means higher trailer tail height.
Another consideration:
Since Airstreams with rubber axles do not have equalization between the
axles (does not apply to single axle trailers of course) it is important
to get them level. If the trailer is low at the front the front axle will
be more heavily loaded. If the trailer is high at the front the rear axle
will be more heavily loaded.
[I put "XX" for the height as the specified height is only for that
particular trailer model.]
Al