Yes, you are in the right area and if you can see enough to spot a silver colored "can with two bigger lugs on each side, that is what you need to be able to reach.
Click this snip to see better!
When you look under the seat from the front, you should see something like this picture!
The silver can looking thing on the left side is the solenoid that does two things for us. One big one is it connects the chassis battery cable on the left that may have a red tape on it, through the contacts inside to the coach battery cable on the right side. The coach cable may have yellow tape on it as an ID?
Sometimes the tape get hot and gets old and comes off, so no surprise if it is not there!
When we run the engine a signal comes down from the front on the little wires and makes this close like a switch. That lets the coach get some charge back as we drive!
Second is a dash switch that is labeled something different at different times . Maybe AUX? When we push that and hold it, it connects the two batteries together like a "jump start" and we can start the engine , even if the chassis battery is weak. We get a jump start without getting out jumper cables!
But what it does for you now is gives you a place to check the coach battery voltage without going underneath to get to the batteries where they hide them!
If you can get one meter lead on ground like most any metal floor or seat and the other lead on the right side, you should be reading close to the battery voltage.
While there, you can also go to the left side and see the chassis voltage!
Just for future if you want to while there, you can also see if the solenoid is actually doing it's job?
If the coach battery has had time to get stable and not be charged or used for a few hours, you should see around 12.7 on a good fully charged coach battery on the right side!
Then if somebody starts the RV engine and revs it up and down, you should see that same point go up and down as the engine alternator puts out higher voltage at higher speeds! The reason you see the coach go higher is because you are seeing it is connected to the chassis power! Right and left should read the same as they are connected!
Then the black gizmo to the right side is the relay that the battery disconnect switch moves. NOT involved right now but that is where the switch opens and closes the relay . Power comes in from the coach battery on left and is connected or not going out to the right!
For the current problem, if you see 12+ volts on the cable from the coach batteries, you are good on battery being charged and having good clean cables to this point! No crawling needed!
