Hey 
@Gburn770.  Please put your general location in your 
profile. It will help us to help you if you have questions that are affected by location/climate.
The commonly recommended minimums (assuming full-sized chickens) are 4sqft/bird in the coop, 10sqft/bird in the run, 1ft/bird roost in the coop and 2+ nest boxes for a group that size.  Your numbers are a little tight, but better than pre-fab coops.
I used a tractor similar to that for the first 4 years in my 1/10th acre backyard.  It worked, but was very heavy at 7'x4' and was hard to maneuver.  If you have a larger flat property and mostly are pulling it straight, it is much easier than if you are constantly trying to turn it.
Be prepared to park your tractor in winters (assuming you have snow/ice/mud).  Those winter parking areas will have all grass killed before you can move it again in the spring.  Chicken tractors can be fairly secure, but never as secure as stationary coops/runs since you can't really guard against digging critters very well.
As much as I liked the advantages of a chicken tractor, I gave up on it and I was only dealing with 3 chickens.
Here is a picture of my tractor.  It had a 2"x6" base and the rest was an upgraded 2"x2" pre-fab coop. 
View attachment 4034915