Thanks to all for the helpful responses. Now that I read my original post and the responses, I realize that I did not accurately describe my choices.
Actually, I will be leaving from Jacksonport State Park near Newport, Arkansas. When I said I-55 "from the north" I was really thinking only of the construction and traffic around Memphis. So what I said was true, but somewhat misleading.
I could go "UP" toward Dyersburg, or "DOWN" toward Memphis. That is the real choice I have to make. The next stop will be in south central Tennessee at Davy Crockett State Park in Lawrenceburg.
Sorry for the way in which I originally stated the case. I will still appreciate any comments or suggestion--even those who would give different advice in light of this clarification.
Fortunately this trip is over a month away so we have plenty of time to consider alternatives.