You really should have an isolator in the circuit. It does two things, protects the cluster from being damaged by shorts in the trailer wiring, and makes it so the trailer lights get power directly from the battery, not through the cluster. The turn signal/hazard lights are controlled by the cluster, not a usual auto type flasher. A short in the trailer wiring could cost you a cluster, which is not cheap.
There are several on the market, not just the BRP one, although you may have to do some custom wiring mods to use one not made specifically for the Spyder.