@Chris_Kornelsen I’m struggling to tap into personal experience (or that of anyone else I know) whose digestion got worse going on keto. On the contrary, many (including myself) found that cutting out the carbs resolved GERD and other indigestion issues. So I’m having a hard time offering advice to your question below…
… other than to suggest that it IS the whole grain and fruit that is creating the indigestion.
The optimal amount of carbs is zero. Your body needs no carbs for health. Your body, however, does need protein and fat. So to ask how much is the optimal amount of something you don’t need to be healthy is kind of like asking how much cocaine does one need - optimally - you know … at least for one who is a cocaine user.
The optimal amount of something that is likely causing you health problems is clearly less than the amount you are currently ingesting.
I would suggest you experiment on yourself and see how much you can get away with without experiencing the digestion problems you are experiencing. If it’s more than zero, ok then. Otherwise, stop eating carbs 
(ps - you’ve chosen the heading “Need low carb tips” for this post, but more accurately, one might call it “Need high carb tips”, no?)