Here's where I am on all this; I appreciate you folks hanging with me as I think this through.
My bike has fenders, which seems to rule out racks like the Yakima and Thule models which grip the top of the tires.
I'm thinking my best strategy is to get a bike tube adapter like the one bikendan pointed me at, and to plan on removing the battery from the bike when it travels on the rack. This will take the weight down to something like 25-30 pounds, so I don't need a super heavy duty rack, and I can use a sturdy rack like the Swagman.
Not ideal, but it seems to fit the circumstance about as well as anything. Am I missing something here?
R