High Sierra in a MacPro 3,1

I have installed High Sierra in my MacPro 3,1 using Dosdude1 patcher and algorithm. However, the recovery HD was not created (don't know why). To use the patcher you must disable SIP, which must be re-enabled once the installation finishes. But I cannot do it from the Recovery HD because I don't have one. I have tried to do it booting from the patcher itself, but it does not work and ask you to boot from the Recovery HD. So I am engaged in a Next-For cycle or whatever name is used now. I created a USB flash with apple's High Sierra to boot from it but it neither works because, apparently, the installer checks MacPro Version and does not boot at all. I need to know which file (or files) I have to edit in the official apple installer in order to bypass the MacPro version check and be allowed to boot from the USB. Is that possible at all? Please explain. I know that I have seen something similar to boot Windows from a USB in unsupported MacBook Pros. Best, Juan de Marcos

rEFInd can enable/disable SIP. For your purposes, I would install rEFInd to boot from a flash drive. You might have to edit the refind.conf file to turn on the SIP feature.