I don't think I have ever seen them. Who makes them? That's a lot of stress on a rod holder.
Do you currently have a method that you are trying to improve upon? Must be a PIA with outboards.
Honestly I think your best bet is a slightly smaller inflatable with a removable bottom that packs up into a bag you can stow with a small 2-6hp that is 60lbs or less with an internal gas tank. A larger inflatable is just going to limit your options like you’ve been wrestling with. Don’t ruin your gunnels for an inflatable