The ride height spec and how it is measured will be unique to a specific chassis configuration, so unless somebody else has a Magnum chassis with the same capacities as yours, getting advice on the internet is risky. Don't let somebody give you Roadmaster chassis specs - your 1997 chassis is not a Roadmaster! Later Beavers, maybe 2002 and later, will use a Roadmaster chassis, but not yours.
This blog item won't answer your specific question, but will explain some of what you need to know to get the right answers.
Motorhome Magazine Open Roads Forum: How to measure ride height on a DP?
One of the Beaver-specific websites might have some specs. Here's one: Beaver Info Page