Wedding Ceremony in the Woods

So, my fiancé and are planning our June 2021 wedding, and will be having our ceremony in the woods at an outdoor chapel at the camp I grew up at, mid to late afternoon. The reception is planned to be indoors at a separate reception venue. The struggle I'm running into is getting my mom and grandma to understand my vision. Being outside, it won't be a formal event, but they seem to think people will show up in jeans, and it seems like they cannot get past it being outdoors. We plan to have a wedding website with a section dedicated to attire where we will explain that heels are not a smart decision, but also that the attire will (likely) be either cocktail or semi-formal. I've seen examples where folks literally spell out attire suggestions. My bridesmaids will be in long dresses with a slit and flats (I hate short dresses on bridesmaids) and my FOH and his groomsmen will be in suits. All of this explained, they are still extremely skeptical. I guess my question is if I'm being overzealous, or? Obviously I cannot control what our guests show up in, but hopefully the website will inform them. I don't think cocktail/semi-formal attire is too dressy for an outside ceremony/inside reception. Am I missing something?