what's the correct order for surge and voltage regulator?

The only device I have ever encountered that really cleans up throughput power is an isolation transformer. "Cleaning Up" does not mean regulate but AUTO-TRANSFORMERS offer ZERO isolation. The definition of "throughput" of course means this does not include use of an inverter in the circuit.

The very most PRECISE active regulator and filter I have ever encountered is my SOLA* ferroresonant "Line Tamer" (30-amps) with a MAGNATEK full isolation transformer.

78-148 volts input = 120.0 volts output +- .7 volts. Of course at 60hz.

This is "medical grade" voltage regulation and filtering.

Nothing but nothing beats an isolation transformer to filter transients and harmonics.

*This one is special. It has a "tickler" transformer circuit.

All extremely impressive. Truly phenomenal performance. And goes dead as a stick in a blackout.

I've seen a good setup using a PI surge suppressor, autoformer, then the PI EMS. This way, a large transient gets stopped, but the autoformer can do its job. If the voltage is useless where even the autoformer can't help, the EMS just turns the lights off and tells everyone to go home.

I've been interested in the "hybrid" inverter/converter that can take a low voltage and boost it from the batteries, so everything in the RV always has 120VAC no matter how dirty the shore or generator power is. I forgot who makes these inverter/converters, but they would be useful. That way, one just needs a surge suppressor, and that's that.

What form of transient voltage protection do any of these Recreational Vehicle voltage regulation gizmos use?

Get a good EMS like Progressive Industries and hook it up directly to the pedestal. It will do both functions you are looking for.

Call me if you wish.

I have mine: pedestal, voltage regulator, surge protector, then trailer. If the surge protector were first, it would shut down not allowing the voltage regulator to do its job. My voltage regulator is always in circuit. My stuff is internally mounted. I want it to be as foolproof as possible. Just plug in and I'm set to go.

Transient voltage protection (MOVS) etc. should be first in line. Why? Because high voltages cannot hurt them while transient voltages can slowly but surely degrade the class H insulation of a voltage regulation transformer. I like devices that employ both AVALANCHE RETIFIERS and MOVS.

Voltage regulation is another subject.

But the ordinal above is hard to argue with.

I don't use my Auto-former often but when I do its Pedestal, Auto-former, Surge Protector then RV.

Yes if the protector is the type that will cut power for low voltage.
If it is just a simple surge protector (not EMS type) then it may as well go first.