Hello and welcome to the forum! Looks like your post fell through the cracks.
Have you looked up the repeater on the main MYGMRS.COM site? If you are a member with a call sign you can look up the owner and make a request.
I just looked it up and it is listed as an open repeater. Go to the map and zoom in on Nor Cal its right there. Click on the repeater and it will give you the tones and info about it. Good size repeater.
Good luck!
This is right from the specs on DPD's ad for 50 ft of RG8x.
Performance: This cable is fine for short runs from your device to an antenna, but not recommended for critical loss applications above 400 MHz at this length. Using this cable at this length on something like ADS-B, is probably going to create some loss.
All he sells is RG8x.
Very likely will work. I have done that far at least in mostly wooded conditions using the Wouxun KG-805M radios (which put out the full 2 watts on MURS and are very good radios IMO). Have reached five miles base to mobile and base to HT from hilltop base with rooftop antenna. That is the furthest I have tried so far, that reminds me I need to go out and test at further distance.
As you said the only way to know is to test it yourself.
Here's a article you may find interesting.
https://www.buytwowayradios.com/blog/2024/05/why-wouxun-gmrs-radios-do-not-include-programming-cables-and-software.html
I was attempting to answer the OP's question. In the short term (he mentioned a 48 hr window) Sat phones would be the most likely to be working. That is what they are used for normally, when there are no other means available they work almost everywhere.
But you are right in saying "It really depends on what is meant by SHTF". The situation will be different depending on if it is a local event or regional, national or world wide.
I think you answered your own question. A sat phone or text messaging device will be about your only option. My sat phone provider says they will not disconnect service for at least 60 days after last payment is received and maybe longer if payment systems are down as that will be out of everyone's control.
Channels 8-14 are not available for GMRS mobile radios to use(though it may be able to hear them). Try 1-7 and 15-22 check that all "privacy" tones are off. Read the manuals to find out how.
Line of sight between antenna's is most important. I can reach 91 miles to a repeater with my HT with my rooftop antenna and living on a hill with clear line of sight to the repeater.
LOL! I guess we need to define just what a CCR is. Midland and Wouxun are both made in China MXT-500 and KG-1000G are about the same price. And if the Midland is not "cheap" then neither is the Wouxun. So neither is a CCR? Is it where the company is based that matters?
It probably comes down to the differences between MURS which is VHF and GMRS which is UHF. If MURS works better for you the KG-805M is a good radio. I have several and they work great. Have reached 5 miles at times through partially wooded terrain. Also work good hooked up to mobile and base antennas.