There is a project to inject small aluminum granules into exhaust, so they melt when leaving engine but solidify on contact, which would be a good way to cover your landing site with solid aluminum layer. A rocket engine could easily melt a ton of aluminum per minute.

That's still throw ejecta in the air though and sounds just like a recipe for disaster.

If you hover high enough in vacuum, gases have enough time to disperse and won't throw ejecta that much, but those melted aluminum droplets can travel relatively unimpended and solidify on contact. You land only when you have good solid surface.