Few things here.
Put the dog away every single time food comes out. It is a huge distraction. My second will not eat anything and will feed it all to the dog. Ours goes in the crate.
We do use a booster at the table and not a high chair. However, my child gets distracted so I will take 10 minutes before the rest of the family sits down and get some food in him first that way with just the two of us at the table.
I think you can do snacks on the couch, but not every meal.
Do not put more than 2 bites on the tray. If you ton it up they will throw it off. And hide whatever else you are going to offer. I make up a plate and put it behind me and slowly bring it out as he's eating. Also if there is a lot of stuff on the tray as you go through the meal wipe it clean and start back with the 2 bites.
To keep it interesting vary the texture. If you see behavior coming on, then switch texture. Or flavor. I try to do crunchy, sweet, salty, and soft all in one. Let me give you an example. If we are having chicken. He is eating eating eating it and then now he's throwing it on the floor. Then I would offer a carrot stick, veggie stick, something totally different. He eats that, and then I can switch back to the chicken in a few minutes.
We have a rule if he throws more than 2 times the meal is done. I have only recently started this at 17 months. We had a LOT of food throwing problems and I was beyond sick of it. So he knows. And I will say that he gets very pissed when I take him down from the table, but it has basically curbed him throwing any food.
At 14 months yes there is experimenting and tasting, but in my honest opinion food throwing and flinging only gets worse if you allow it. So again, if you keep what is in front of him to '2 bites' only then if they decide to launch it it's not a huge mess. And they really aren't as likely to do that with only a small piece of food in front of them.
And put those dogs away when food comes out!!!!!!!