Peak Ozeblin
As soon as you see that the car ride to the starting point of the mountain climb takes three times as long as the climb itself, you know there is a catch. The hiking trail actually starts much further, but I don't see any point in walking for two and a half hours on gravel road.
If you look at the satellite image, you will understand why I recommend visiting Ozeblin, not on foot, but by bike. The area is full of macadam roads which, at least when I was there, were in relatively good condition, and it is possible to make a circular tour from Udbina.
I have marked three parking places on the attached map, and you can choose which one to start from. From the northernmost parking to the top, from which the view can be seen on all five sides (also look above), you need about twenty minutes of climbing along a beautiful hiking trail. It takes about 45 minutes from the middle parking, and more than 3 hours from the parking at the Kuk pass. Keep in mind that if you choose parking under the peak, it is more worthwhile to access it from the north (10 min).
Given that the condition of the dirt road depends largely on the weather and the work done by Hrvatske šume, it might be best to get to the Kuk pass and then drive to the top as far as you can and want.