Those specs are the maximum for that converter, but if you're smart your trailer will have LED tail & stop lights, just the like the RAV4 and pretty much all modern stuff these days, and the trailer's lights (including marker lamps) won't draw half that much. That's why I said I'd look hard at using the cigar lighter socket for power.
If you think you'll actually be using near 10A on trailer lights, then I'd run a dedicated wire from the front, but if unless you're going with incandescent lamps -- and a lot of them -- I'd think using the OEM cigar lighter circuit will be adequate.
If you think you'll be running, say, a Peltier thermocooler off that socket at the same time your towing, that might be a good reason to run a dedicated wire. That wouldn't be an unusual situation for camping.
------------------------
Back in the day, I used to construct my own European-to-US tail/stop/brake converters for my cars: four Schottky diodes is all that's required, if powered by the tow vehicle's existing lighting circuits. I could use standard diodes, but the 0.7v forward voltage drop made the trailer's light just a tad dimmer than they had to be. Back in those days, you had to swap in a different flasher relay when you towed, or the lights would flash too fast when the trailer was connected -- all the OEM flasher relays' timing was based a thermal unit on a bimetal strip and required a certain lighting load for the flasher timing to work out correct: change the lighting load, change the flash rate. Then electric flasher relays became affordable and that problem went away, with the side effect that you could no longer know you had a turn sig lamp burnt out by noticing the remaining lamp flashing too fast.
Now that many modern vehicles monitor lighting circuit power draw in order to illuminate a warning lamp that there's a lamp "burned out", adding trailer wiring sometimes requires a bit more thought.
Later, I had an '89 Aerostar with factory tow package that I had to reverse-engineer one day, and Ford's package had a lovely bank of three relays to isolate the van's lighting power supply from the trailer, with the unfortunate side-effect of occasionally blowing a very well hidden and hard to access fuse, about once a year I had to tear out panels to get at it until I replaced it with a circuit breaker. It was also a completely deactivated relay module until activated but a feedback loop in the factory tow adapter harness, which was unobtanium at the time, and which I reproduced using the wiring diagram from Ford that had a misteak. Lots of fun! Then two other later Aerostars with variations on that theme, which I extensively documented about six years ago . . .
For my own reference, and the search engines:
Ford Aerostar tow wiring: three eras and versions.