Hi @Frances4982
Whatever you do....don't use Evolve! (or any large property mgmt company). Just type "Evolve" in the search the community box and you'll see what I mean. They will insist on being names as primary host and you will loose all the reviews you worked hard to get if you have to terminate your agreement for non-performance.
Extra Guest Fee
Your $50 extra guest fee is a bit high and I would definitely remove that from the listing, especially in slow season. It's a barrier to booking for many guests.
Marketing & Optimizing Your Listing
You can use social media to help advertise your listing (Instagram, facebook, etc.) Do you have a local neighborhood app like Next Door? Is there an online media page for the RV park you are in? You can also ask another experienced Host or Co Host to optimize your listing for you. Airbnb has a Co-Host platform and there are independent consultants that do that as well for a reasonable fee. You could also consider some other RV sites to list, but I don't know much about those...you'll have to do your own research on that.
The summer season is over now and Texas has a slow period until the snowbirds start traveling in the winter. Expect it to be slow until probably Jan/Feb. The next busy season is usually spring break in March in the Texas market. You might see some guests wanting to head to South Padre Island for spring break. I would highlight that in the listing.
Custom Promotions
You can start using custom promotions, but be sure you read up on them and understand that whatever discount you offer on the custom promotion can be stacked on top of other discounts (weekly, early bird, last minute, etc.):
Create Custom Promotions
https://www.airbnb.com/help/article/2982