I also think you'll need to use a "checkboxes" field type (even for one checkbox input) and use the "Display Value" to populate the text to the right of the input (regardless of what you've got the form labels set to). The actual field label (label.mktoLabel) for a checkbox and/or checkboxes field type is what moves above/left of the checkbox, the display text is also a label, but doesn't have the ".mktoLabel" class on it.
Once you've got the field setup that way, you can use some CSS to display the "mktoCheckboxList" as a "flex" element and then add the flex-direction property "row-reverse" to put the checkbox to the right of the text.
In terms of getting one field to display differently than others, I prefer to use a "fieldset" and put the odd-ball field inside that fieldset so that I can write CSS for all checkbox fields and then write separate CSS for all checkbox fields INSIDE a fieldset. In this way you can carry two "sets" of styles for each input and use fieldsets in the form editor to kinda change how they show up on your form. Another way to go about this would be to write CSS specific to the field's ID value but Im not sure that'd work for this application.
If you're able to share a link to preview a page with this form on it, I'd be happy to dial in some CSS you can just snap into play on your form's Custom CSS to get this working.