SVBONY SV219 Dovetail Mount Plate, 210mm 8.26 inches Universal Dovetail Plate Compatible with Vixen Dovetail Saddles, Telescope Accessories for OTA Equatorial Tripod Sky Astrophotography

Something like this "should work" for your purpose. (Double check the screw holes sizes) https://a.co/d/0blsjdeu "However" the core issue here is that your mount is already severely overloaded. Putting a DSLR and a long focal length lens is going to be a bad time.