...my question beside your itinerary to Odessa: why do you pass via Constanta ...
OK, now everything is clear
I'll not go to Costanta
I'll make any possible effort to pass the river in the between Izmail (Ukraine) and Tulcea (Romania) without windind-up to Moldova.
So ... Odessa-Izmail-Tulcea and then .... wow ..., upstream Danube strightforward to Budapest!
ConRAD