sure

you can send from PT via the interface and then record the output of the FVP as a new track
or
you can put the FVP in the channel insert of that track and use it ... live ... so to speak

the output from the PT interface will be at line level so you will need to do a levels adaption ... that is if the FVP doesn't have a line input.

It is not that crazy to pad a line level down to Mic level so as to gain it up again using your favourite Mic-pre.
This is done for effect and will degrade signal to noise ...

remember this is for effect and characture ... yes ?

Yeah. I just want to be able to have a dry track. And then be able to add effects later. I just don't want to have to keep adjusting while I'm tracking. I want the flexibility later when mixing. In the manual of the FVP, it doesn't really explain how to use it in that manner.

either method will work

I don't put the FVP right out on top as far as Mic-pres go
BUT
it's added features make it very useful in the mode you have suggested.

If you where to use an ultra clean or even just a clean Mic-pre,
then you could use the FVP as an effect unit and while in mix down mode dial in the desired amount of any of the features the FVP has to offer.

... at line level send return ... the specs suggest 27dBu

Signal to noise ratio relative to max headroom (27dBu) = 121dB

and EVEN the ClassA descrete mic input can be used.

a simple resistive balanced pad of between 20 to 30 (more if you like)should be enough to drop the line level from the PT interface such that you can dial in that ClassA gain stage.

However,
I suggest a good transformer and an adjustable/selectable pad to make it all look more like a mic source and give you good control of tone
...
this will can the PT interface (or any other source equipment) safe from the possibility of damage from the 48v Phantom ... accidental or not.

this IS a very good plan
especially if you record yourself
it is so very hard to dial in some of these controls while singing
much easier to do it later