Like Bob, I don't think there is room between the top of your slide and the existing awning to add a topper.
I know on some of the models we looked at, we were told the main awning serves as the slide topper. I didn't care for that explanation.
Everyone says the main awning isn't to be left out during hard rains or winds so what good would it do protecting your slide when rolled up?
I think your unit would need to be equipped like our new 8529IKBS with a slide topper and then a shorter main awning. Our slide then has added to it a 'patio awning' which helps make up for the shorter main awning. (see picture)
2016 Flagstaff 8529IKBS Diamond Package 5th Wheel-Goodyear Endurance Tires
2017 Ford F-Series SCREW 4x4 - Factory Puck B&W Companion
TST Tire Monitor w/Repeater - Sinemate 3500w Gen.
Days Camped: '17=30 ☼ '18=51 ☼ '19=58 ☼ '20=55