Can't help with Mexicali. We go to the Purple Pharmacy in Los Algodones/Yuma, use the Quechan Casino CG, no hookups, low cost and plan to be there next week. We take the car to the res parking lot at the border. $7 to park the car. Can take the RV there and I don't have a RV parking cost. It's about a 2 block walk from there. Talked to several people that are satisfied with dental work there but have no personal experience, but search the internet for information. Perhaps a option as it's not far from Mexicali.
Suggest you review safety and border crossing waits. A few weeks ago there were reported US entry car waits of 11 hours at some border locations. :( No mention of walking entry waits. Last year it was 45 minutes for me at Los Algodones. The US border dogies always ignore us. :B
We've never been stopped going into Mexico unlike coming back. Google Earth will show all of the above.