My experience is based on my brother-in-law using them. this data will be a couple years old.
About 100 a month for up to two hours of talking and two to three dollars a minute after that. You want an iridium phone. Not sure what the phone rental will be on top of that.
I was heading that direction a few years ago. the cost of a decent phone was around $1000 new and about 2/3 of that used. Then star link came out and I haven't looked back. The cost of the phone and a month of service puts you close to the cost of star link. I turn my star link service on and off as needed. You can either mount it or just throw it on the dash. You now have phone, texting, and internet. If you use a mapping program, uploading new areas is almost not needed.