In my experience, if youre shooting a high-stakes wedding, honestly just stick with the Canon BG-R20 Battery Grip. I've tried many setups over the years and while the older Canon BG-R10 Battery Grip physically fits, it wont support the new high-speed features you really need for the R5 II sensor. Its tempting to save cash, but dont risk it on a paid gig, basically. Let me know if you need battery tips tho!

> What are the best vertical battery grips for Canon EOS R5 Mark II? Im totally pumped for your wedding shoot! For pro performance, definitely look at the Canon CF-R20P Cooling Fan Grip. This thing is amazing because it adds active cooling for heavy video sets! Alternatively, the Canon BG-R20EP Battery Grip with Ethernet Port is fantastic for high-speed wired data. Both options provide incredible utility and justify the extra investment!

TL;DR: Stay far away from cheap third-party grips for a high-stakes wedding. If you cant afford the official ones right now, just skip the grip entirely and carry extra batteries in your pocket. I really have to warn you based on a horror story from a few years back. I tried to save some cash using a generic knockoff grip on a previous body during a ceremony in a drafty old church. The plastic flexed just enough when I was using a heavy zoom that the pins lost contact. The camera totally blacked out right as the couple started their vows. I felt like I was gonna puke. Chicago weddings are intense and you do not want your gear failing because of a sixty dollar piece of plastic. The Canon EOS R5 Mark II is a sophisticated beast and it draws serious power for that stacked sensor and the high-speed autofocus. Using a non-OEM grip is basically like putting budget tires on a Ferrari. Even if it physically fits, the voltage regulation might not be up to spec, and you risk throwing a battery communication error or, worse, frying the motherboard. I know dropping more money after buying the body hurts, but honestly, your reputation is worth way more than the cost of a proper accessory. If the budget is tight, swap batteries manually and keep them warm near your body. Its better to have a slightly cramped hand than a dead camera in the middle of the reception, imo.