It maybe worth trying to introduce the food at a different time and place - say on a towel out in the back yard rather than in the highchair. Also perhaps a small amount of food at a time just left out to discover. DD here loves the frozen vege mix (cooked of course) and picking out the different veges. She seems to make less mess as they are small and require some precision to 'catch'. Sucking pasta sauce off pasta is another fav as is flicking fried rice EVERYWHERE!
Messy as it is DD also loves eating in the pram - arrowroot bikkies all over the place. FWIW DH is a neat freak and is not allowed to wipe and spoon feed as DD1 became obsessive about being clean between mouthfuls.
Belfie - I would be stressed about gagging etc too but you are doing a great job! Let us know how you go. x