chev 350 longbed topper
when you say 'topper', do you mean something which is about as high as the cab, usually with windows in the side and a door or lift gate in the back? Or do you mean something flush with the top of the bed?
If the former, it may or may not be a problem for the pair of you. If so, and you don't have family or friends who can help, you may be able to attach brackets to it, then use jacks like they use for slide in campers to lift it, then drive out from under it.
If it is the latter, then you should be able to handle it. Probably don't want to try it if the wind is acting up though
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I cover the front 1/3 of my bed with a custom flush cover which protects the generator and provides secure storage, and the back 2/3 are alway open. The same company sells a complete cover, with hatches to remove to tow the 5ver, but my pin box was too big to fit through the holes. On my previous truck, I had a 'roll n lock' cover which I could just roll forward to expose the hitch. There are also some 'fold n lock' covers which might do the job as well.