I do think to assess your own safety and the safety of your horse, each rider has to be honest with themselves and their abilities and stay within them
“A good horseman is safe at all times, provided the horse stays afoot.” How many of us hold that inside and strive for that? Realize that it is largely your decisions (whether by mount selection, choice of riding location choice of work asked of the horse) that most influences if your horse “stays afoot”.
Have trouble being tight in the tack? If possible, take lessons with a strong equitation instructor. Yes, you are an eventer… keep the good and discard the irrelevant-to-your-discipline. Be open minded… if you selected a good trainer, there is very little in learning proper balanced position that is truly irrelevant in our sport. Both a strong leg and strong and balanced core are never a detriment. Watch and listen on foot to others lessons, and see if you can see and understand the deficiencies that need work before you hear the instructor’s corrections.
Can’t afford lessons? Read good, test of time books. BHS will not steer you wrong. Go spectate at h/j shows and watch watch watch. Learn what a strong but sympathetic rider looks like. Determine what suboptimal riders are doing and why? How does that look and correlate to the team’s performance? Try to find trusted eyes on the ground or at least a bored friend who will video you. Very worse case, try to get decent video from a phone set on the fence post to view a swath of the area your working to critique later.
Audit everything you can, and don’t turn your brain off. You will always learn, whether what to do or what not to do. Clinician too harsh, unfair? You see what makes that the case, weigh against what they are trying to teach or accomplish, consider what you might do if you were riding in that situation. Put your horse first, and think about whether you would go along to get along, or call it a day. Which would be better for your horse?
Drop your stirrups in your jump saddle and actually post. Two point the canter. Jump fences. Too hard? Still necessary. Do you want to event safely?
Maybe you would rather not do the work to improve as needed for what you want to accomplish. Maybe you cannot. Openly and honestly think about whether this is the sport or level for you. Maybe it’s not, or maybe it’s just not at this phase of your life. That’s fine. That’s honest. And that’s being fair to the horse.
As to keeping the horse afoot, I am a huge proponent of Jimmy Wofford’s school of thought.