Hi Leo, I know you hate Explorer's Checkbox mode and don't want to modify your one. However, I cherish the little hope that it will not be difficult for you to add 2 simple options to current mode as is on picture? As result, only 1 select / check action will need instead of 2
You can use the middle mouse button, without checkbox mode, to do that already.
Long time ago my middle mouse button assigned to Enter action and I don't want to change it.
In this way it do nothing, 
This additional options can bring more flexible selection.