What is the other dimension to the deck area? You indicate you have 101" to place a spa that measures 89". Will you have room to deal with the cover? Everything gets bigger when it gets home and the Optima is going to overpower the space you are placing it. If you split the difference that leaves 6" on either side and no option to access the sides to install a cover lifter, much less the need for future service access.
Also, the spa must go into placement while it is flat, 89" wide, as there is no room to "lay it down' from a vertical position.