How can I include/exclude large, lumpy transactions from Net Income report?

I want to create a tag or similar for large, lumpy transactions (e.g. vacation, furniture purchase) so I can easily toggle them to show or not show up in the Income & Expense report. Basically I want to see what is my net income for the month, then what is it if I exclude those big TXs. I created a tag for these - call it "slush fund." The reports don't let you exclude a tag though, only include. I have upvoted similar requests here to add this feature to exclude tags; this would be super helpful. However I can't figure out any workaround to achieve what I want. Marking them all as Exclude from reports isn't something I can then toggle on/off in the report. I tried creating a second tag that's essentially "no tags" that I would apply to all the non-slush-tagged TXs (so I could then filter the report to include only the no-tag tag) but there is no easy way to apply this to all other TXs without doing it manually. The only solution is to create a slush category, since I can exclude categories from reports, but this loses the category data I want to maintain to see within those slushy purchases. Please can someone help me find a way to do this.