Steven, apart from authorization object you can go for other options like
1. Restrict the fields via SHD0 and assign the same variant to your quotation document type in VOV8. You can also define user specific assignment for transaction variants.
2. Take the help of your abaper to apply the logic accordingly at FORM USEREXIT_MOVE_FIELD_TO_TVCOM_H and FORM USEREXIT_MOVE_FIELD_TO_TVCOM_I to restrict header and item texts of include MV45AFZB.
However it depends totally on you as if you want this restriction to be applicable user specifically or for all users. Rest please feel free to ask in case you need any further assistance on this. Thanks.
