Yes, disconnect at the meter, on the pole. It is a Combo type unit ( if I understand what you are asking specificaly.) The meter portion and the Switch portion are butted up against each other. The switch is below the Meter, no conduit (or any space for that matter) between the two.
The disconnect switch box does have lugs for 2 services. One of which I already have in use to a 50/30/20 RV pedestal which I installed. The one I installed is working fine. The GFI's and a hard wired surge protector's ground fault detector work as they should. So, I've done something like this before, just not so far away.
Running 240v to the RV pedestal(s).
The pedestals have preinstalled
1 - 50a 240v breaker
1 - 30a 120v breaker
1 - 20a 120v breaker
1 - empty 120v slot
I measured the Voltage nuetral to hot to be 124v but I didn't think to to measure hot to hot the last time I was there. The Transformer come straight down to my meter and there is no other service off the transformer. They installed the transformer for me at my request last year.
The 4/0 is a good match for this setup.
At the distance, it can carry 75 amps if needed.
You could lower to 2/0 cable if only want the 50 amps and no room in the future.
Here is a diagram I found in my file for assistance on services , it is of standard service with the meter and disconnect feeding a panel.Yours is identical with the exception of, your pedestal is not at the same structure of the meter/disconnect, so it requires the separate ground rod and connection.On a home, the panel is normally in the same structure.