There is an interesting app called RV Checklist. Costs .99. Check it out, you might like it.
I too am a first timer, and have been developing a checklist. Our first inaugural trip is this coming weekend. Its a short 30 minute trip for an overnight campground. Our biggest hassle has been in organizing the trailer, making sure we have everything we need, but not overdo it and add too much weight. Think about what we will use, what would not be used, what is a must have, can all add up to frustration. Hopefully the frustration pays off by not forgetting something.
Many people over pack for their trips, and I am trying to avoid taking more than we will ever need. Don't need a fully stocked pantry, a few canned goods for the first couple days until we reach our destination, where there is a grocery store nearby. Same for bulk food items, and perishables. Only take what we think we will use the first few days, after all, Walmarts do have large parking lots.
The #1 thing though, leave the electronics home. No TV, no DVD, just a radio, board games, cards, etc. The only thing I am taking is my laptop, provided I get the utility for my camera to work, and only for taking night shots of the sky, otherwise it stays home too.
It's a vacation, a time to get away from it all. Enjoy it.
BTW, like the clothespin approach, consider it stolen.
One other thing that is worth consideration, invest in research time before your trip. Find campsites along the way that appeal to you, reserve the spots, but verify you have everything you need to camp there. For example, you can go to reserveamerica.com and reserve camping spaces at state parks, but read the fine print before you click accept and submit, there are details in there that can prevent you from getting your space, and forfeit your fees. Some state parks require a daily park pass, so where do you go to get one. Some will tell you, or have links, others are not posted, so call the campgrounds and ask. I did that before booking two sites in Colorado, and in Nebraska, you purchase them online, for the day you plan to use it. Call it your pre-trip itinerary. It's one less thing to be on your mind as you leave(just dont forget the paperwork on the printer).