When I rode from Washington, DC to San Diego, CA I had a grand route all planned out. Starting with the second day I found myself headed a different direction so I could avoid nasty weather. From that point forward I just started the day with a general direction in mind and set the GPS for some town I thought would be on the way.
Most of the places to stop and fuel up or eat along the highways have small booklets with discount coupons for hotels and motels. I used those coupons almost every night and always got a room and at a reduced price.
I think what you will find most surprising is that people across America are for the most part, helpful and kind. If you get into trouble there is always someone to lend a hand.
I don't think you need to hire a travel agent to help you with this. There is enough assistance right here to help you with most issues.
The scooter issue though is an interesting one. I don't know of a great solution other than the rental of a motorcycle. I am not aware of any place in the U.S. that rents Burgman scooters.
My trip across the U.S. took eleven days. Not every day was a long hard ride. From the motorcycle sites I found it looks like a rental would run you about $1,000 plus you'd probably have to ship the bike back and that would add to the cost.
One place I found does rent Honda VTX 600 scooters and that is at least close to a Burgman. They also offer one-way rentals and that might work better for you. Take a look at EagleRider.com
Steve