The question is why are you even considering a caravan trip? Do you do chaperoned trips in the Lower 48?
We have done the North 3 times on our own. Each time the trip was in excess of 120 days from MD.
Alaska is not the dark side of the moon. The roads are plenty good, provided one pays attention & drives at an appropriate speed. The roads are not covered with wildlife. Spotting chances are better if you are traveling on your own. If you break down chances are the next vehicle coming down the road will stop to check on you. We have had people stop for us when we have stopped for picture taking.
A caravan offers structure & a degree of security but if you have a breakdown the caravan will not wait for you to get it fixed. A caravan uses CGs just like the commercial ones in the lower 48. On your own you can do the state rec area CGs where you never know what might come strolling through at night.
On your own, if you are a people type person, you will meet plenty of people doing just what you are doing with plenty of tales & advice to swap.