You can make a Clipper into an IFR Trainer as it uses standard parts from the parts list.
So if the bottle, skid units, pipes & etc exist as parts in ther latest pink parts list it should just be a local workshop job to retrofit. You would want the tail fin wing as well.
You would need a new weights calculation as this would change the numbers permanently.
But what is a Clipper but a Raven I/II with a couple of extra bits on?
PS E&OE, not expert opinion, get approval from EASA, ask your engineers, etc
h-r
NB Clipper floats are not certified for commercial work, they still float privately...