Customers have installed their Vue outside of the panel as you can see an example below. The only question I have is how you will power the Vue, with the Vue we do need to be able to measure voltage from both of your phases. It sounds like you are going to power the Vue through a 120v/240v outside plug. As long as you have both the Black and Red connected to each phase of your panel this will be fine.
You can also use audio cable to extend the length of the sensors if you need. We do not sell them, but they are very commonly found on various web sites. 200A sensors have 3.5 mm jack/port and the 50A sensors have 2.5mm jack/port.
Please let us know if you have any further questions.