Yup, 4WD is all about surface conditions and terrain. I have it because I live in snow country. I have been stuck----pulling a boat trailer and heavy boat out of a swamp. That was all about what was under the wheels. Typically, for the average RV'er, it's not necessary.
An SUV will limit trailer weight compared to a truck. An alternative to trailer towing larger trailers might be a crew cab truck and a ramp for old Fido. There may come a time, also, when he needs to be carried into his riding-couch. It's a shame we outlive our pets and have to see them gentrify quickly.