If your AF 990 is like my sister's, the awning prevents the use of a typical RV ladder top piece that connects to the roof.
You could add one more step to the existing ladder.
Factory RV Surplus has ladder repair parts that you could use. I've used them for my other repair / rebuilding parts for my TC.
Under the "RV Ladder Repair Parts" tab they list a
VLPRSBB Premier Step and also the
VLPRBS.2 Black Premier End Caps for attaching it to the 1" aluminum ladder tubing.
You should be able to diagonally fit the step in between existing uprights and then secure it where you want it. Images are shown below so you can see how it goes together.
The step:
An end view of the step:
The end caps:
The end caps installed:
If the problem of pulling yourself up still exists after this. My TC has two aluminum inverted U's mounted on the roof that are inboard from where the luggage rack used to be. Gives you something more substantial to hold onto, while getting on / off the roof. If you can't find these on the internet. You can readily make these from 1" tubing, tubing nuts and foot plates available on the Factory RV Surplus parts site above.
A 1" tubing bender can be used to quickly to do the job, however, you can pack the tubing with sand and bend it over a 3.5" radius. The tubing won't collapse, if you have packed it tight.