This is the route I propose, fun&riding guaranteed, even that this will cost you 1 extra day, but 100% it worths (you need to buy a map of Romania tough):
- you enter Romania from Nikopol (never been there, but surely there must be a big crossing border)
- follow towards north the Olt river, until you reach Slatina
- take right E574 towards Pitesti
- from Pitesti take north to <Curtea de Arges> and continue north to the road named Transfagarasan (the ultimate road in Romania - MUST SEE)
- follow the route north to <Lacul Vidraru> (Vidraru lake) and <Balea Lac>. When you're approaching this point, make sure it's NOT dark or too evening. You are in the highest point of Transfagarasan! Very wild, 2034 m alt.
- you'll start descenting the mountain and follow north until you reach E68
- take left towards Sibiu and find a place to sleep, there is a camping where usually the bikers meetings are taking place, called Camping Dumbrava, address Padurea Dumbrava no.14, Sibiu
- follow north and then take right E60 towards Sighisoara, where is the only medieval living castle/fortress in Romania - awesome
- try the sideroads and reach Gheorghieni and then cross the mountains to Bicaz (beautiful roads and the wildest tiny road creeks in RO)
- take north on the left side of Bicaz Lake towards Poiana Largului and from there follow <Targu Neamt> or <Tirgu Neamt> (the new and old letter spelling) => veeeery nice road
- from Targu (Tirgu) Neamt follow east towards E85 and Suceava
- after Suceava keep ahead until you'll leave E85 and you'll take left towards Radauti

.
Even that it seems complicated, if you buy a map and mark the road from the beginning, it's easy.
You have to go fast from Nikopol to <Curtea de Arges> and then it comes the fun. Try not to be there too late.
If you want,
you can sleep anywhere before Balea Lac, at Balea Lac, but it's gonna be pretty chilly (<10C at night) or after that, in Sibiu.
In Romania you are allowed to camp anywhere, except if you see a specific signage to forbidden that (veeeeeery rare), you can do fire if you're watching it and you're not too close to the forest (resonable distance).
If I were you, I'd sleep at Balea Lac. You cand see the dust and down, the glacial lake, there is a restaurant, hotel (usually full), 100% pure air, silence, rocky mountains around you.
That was it! I hope you'll make the best decision and you'll have a GREAT and safe trip!!!!!!