Wanting to explore a threesome as a couple

Hi all, I’d love some advice. My husband and I have been together almost 7 years. Yesterday I, 34 F, approached him, 41 M, and suggested we try a threesome (2F, 1 M). I did tell him I’d want some rules before we did that and here they are:

- he gets a vasectomy (he’s willing. I have already gotten my tubes removed).

- he doesn’t finish in the partner we bring in

- we rent a hotel room and not bring anyone home

Is there anything else we should consider before trying this?