KKH, I hope you proceed with Winnebago's recommendations. I don't understand why people persist in recommending Dicor, a product that's intended for rubber, not fiberglass roofs, in direct conflict with Winnebago's sealant call-out list.
Granted, it's probably not going to cause damage and may work OK, but it doesn't provide the adhesive function that Winnebago's recommended products do.
Contrary to popular opinion, silicone, per se, is not evil. One shouldn't use bathtub silicone on your RV but there are many quality silicone products each with it's own specific application.
If anyone is in doubt, check the sealant call out list for your model and year at:
https://winnebagoind.com/diagram/Sealant.htm
Also, watch this video if you're interested in learning more about this:
There's also no need to goop on whatever you use so it looks like seagull s7%$. It's the layer of sealant between the two parts that does the work. The rest is just an unsightly waste. I come from a boating background and knowledgable boaters would never pile sealant and caulking on like RV owners and manufacturers generally do. Can you tell this is one of my pet peeves?