Unfortunately there is no safe way to reopen now or even soon for that matter. The contact is much too close for any precautions to work effectively due what we know of how the virus spreads, which is through water droplets from the breath. Masks aren't fool proof, they need to be worn properly which would be difficult during a session. They also aren't 100% effective, there is still some leakage even with medical grade masks, compound that with fact that you are right up in someone's face breathing on each other, your risk of exposure goes up.
I would definitely be concerned for an SPs safety, seeing potentially multiple clients in a day would increase their risk even with precautions.
Spreading of the virus is also a concern. We've learned so far that a not insignificant amount of people with Covid are asymptomatic, that is, they have the virus and show no symptoms. What if one of the SPs were to be an asymptomatic carrier? They feel fine and can work but are unknowingly spreading it to multiple clients. If one of those clients becomes ill enough to need a hospital intervention they will likely contact trace it back to the agency which would obviously be harmful for the agency and bring unneeded attention. Additionally, the virus takes on average 5-11 days for symptoms to show up, so you can have it and not show any signs. Temperature checks wouldn't be helpful in this case, yes checking temps may catch someone who is symptomatic, but they won't catch anyone who is asymptomatic or someone who has it and is not showing symptoms yet. Another bit we've learned so far is that people may be more likely to spread it while they aren't showing symptoms.
Yet another thing that has shown up recently is that the virus may be harmful to women's reproductive system, which would obviously would not be good for any SPs who would one day like to have children:
https://academic.oup.com/molehr/advance-article/doi/10.1093/molehr/gaaa030/5828941
I know it must be tough right now and I can understand the urge to want to get business going again, believe me, SFT is my go to, but I would strongly suggest that you hold off opening until there is a good enough solution around the problems I've mentioned.
If you were to bring back full service, a potential solution down the road may be using a home-based rapid tests. One is going through the approval process right now, they are similar to pregnancy tests but with saliva:
https://www.cbc.ca/news/canada/hamilton/mcmaster-university-coronavirus-test-1.5530819
I was watching an interview with the person who developed this test and they said that if everything goes as planned it should be available by the Fall. You have the SP do the test before their shift and also make every client that comes through the door do the test.