No there isn't. As Bruce noted Let's Encrypt validates from (currently) 5 perspectives around the world. This will soon be 7 and further changes possible. See: Let's Encrypt is adding two additional remote perspectives for domain validation
A couple options
Use a DNS Challenge. Often DNS Servers are more tolerant of frequent requests. You didn't mention which you use but something to consider.
Use a pre-hook and post-hook to relax the DoS during the renew and restore it after. This exposes you for only very brief times during renew.
You could try a different Certificate Authority but all of them also do multi-perspective validation so I doubt that would help.