That is not the very least. That is a whole bunch of extra work when entire distributions exist just to obviate the need for this. Take a look at tails.
It is, of course, recommended to put it on a usb stick and clean boot hardware off the stick to use it; however, there is nothing stopping you from bringing it up in a VM if you are ok with the trade offs.
Accomplishes the same thing, for less work, and with a much larger already setup base which will be identical to other users, in ways that increase the work of differentiating you from other users.
also, it is possible to jail an environment better.... What you really want on you VM is to jail it onto a network segment with no gateway where its only connection to the outside world is a tor client on a second VM.
Which i care enough to state, not enough to even setup for myself. I have a few tails sticks for the few things I really need a secure environment for....so far that means mostly for times I want to drop off the network entirely in order to work with key generation.