On edit I just noticed you were already in Creel, and it's a month old post somebody rebooted. I will leave the info below for others, It is up to date, I am there twice a year. BTW you can no longer take an RV on the train.
Bill Trimble died a couple of years back, that park is closed. The only place is the Motel Bugamvillas (N 26.4102 W 108.6263), no hookups, turn right as you approach the town from the north and its about 1.5 blocks on your left. There are plans for a new one down by the river if they go ahead. Nice thing about the Bugamvillas is that Maitee, the daughter, will look after your pets if you want to go to Copper Canyon. It is a about a 15 min train ride to the station and be sure to let the motel know when you are coming back or you may not be able to get through the gates. the train arrives back after dark.
You can contact Maitee through her facebook page at
https://www.facebook.com/maiteeyuridia.alcarazsoto?fref=hovercardor you can PM me for her personal email, I don't want to post it. She teaches English.
You need to check when Caravans are coming through, they often fill this park. The large French Canadian ones hit it in March. You want to avoid those. Adventure caravans do it out of Los Mochis & Fantasy out of Huatabampito, so you just have to watch the Quebec ones & Caravanas de Mexico who use the Park. BTW if you do not know the northern access route to El Fuerte (you won't find it on the map and your GPS), PM me, and I will give you directions. The company I wagon master for will be there Oct 18-23 and Jan 18-23. If you want a tour to Copper canyon and of El Fuerte, you may be able to do it a la carte from that company. If interested, PM me & I will ask them. I also know they are thinking of one out of El Fuerte for Northbound RVers in early April and plan to post the info at Totonaka in San Carlos in the Fall. So if you are stopping there southbound, ask about it. You can maybe also arrange tours in Creel from somebody. That may be cheaper. I strongly suggest you do something like that or at least hire a guide up there or you wont see as much as you could. I was amazed at how little i saw when I went on my own a few years back as opposed to a tour. There is also a new zip line that should be on your bucket list. Take along a nice shaped jello mold to have your remains shipped back home in.
BTW El Fuerte itself is very interesting, most peoepl do not realize that. There is also a Bass fishing excursion available from El Fuerte