I have extensive experience installing but when it comes to finishing I don't even have the confidence to tackle the job even if it were my own home. Using the type of sander you mention could also take forever depending on how much material has to be removed to get a smooth uniform surface throughout.
I'd hate to see you destroy a beautiful Walnut floor. Oh maybe not destroy, but take twice the work to fix. Personally speaking, sanding floors is not a DIY project though many will lead you to believe so.
Sorry that's not the answer you wanted to hear.