The 00-04 F650GS tail storage assembly has a flex problem which can result in the loss of the top cover. The 00-05 model has a revised assembly. The 00-04 flex problem can be solved without major expenditure.
There is a brace available commercially, the brace below is larger and made from thicker alloy with 4 fixing screws.
A further modification is to use a lanyard to prevent loss of the top cover like the Kiwi bungy cord solution below.