I agree with @Ann783 , @Susan3850 . If you can go without hosting, that's the safest, but I understand about needing the income. Distancing, hand-washing, mask-wearing, and disinfecting that bathroom will do more good than any snapshot-in-time COVID test.
None of those things is unethical. You can write your own rules. But I know from having had a half dozen tests in the last two months (my industry requires it for everyone on every project), booking a test, getting there, and obsessively checking the website for the results so they have them in time will be a stressor for your guests and will do nothing to protect you.
Asking what they are doing to prevent the spread of the virus is fine. Remember, though, that guests often tell you what you want to hear, so maybe just tell them what the rules are in your home and don't bother asking what they are doing in their homes.
Do stay safe, okay?