@Bridget371 I would switch on professional tools in your account and then apply a ruleset limiting check in to a Saturday only and a minimum number of nights of 5. This would allow someone to stay for 8 nights so they can leave on Sunday and effectively block your mon-sat nights.
I don't really know what you are trying to achieve but you could also block check outs on sun/mon/tues/wed/thursday which would solve this.