Just make sure that there’s plenty of airflow, both for the engine’s well-being and your own.

My deck is a sieve when it comes to rainwater, so that wouldn’t work to keep the water off my generator.

I do keep a dedicated chunk of plywood on hand — I can set the generator outside, and place the plywood on its metal frame. Neither high-tech nor perfect, the one time I needed the generator to keep the sump pumps running, it did work and stayed dry. The wheels and front stand were enough to keep the engine out of the water on the ground.