Make sure you check with the organization that you’ll be racing with on the size of the weights that can be used and how they must be attached.
Another option to bolting the weights to the seat is weld on tabs such as this, https://cometkartsales.com/Weld-On-Lead-Weight-Tab-Steel.html. There uses to be a perch that was bolted to the chassis frame that you could stack weight on. But couldn’t one this morning.
LAD Specialties customer / tony kart / rotax / kt100