My DS is similar age and often has the same determination. Meals that work for us are:
Sausages with mash potato & vege (just dollop the mash in little person sized mouth fulls onto the tray and they can pick it up easily) fish fingers with mash & vege bread sticks with hummous (sp) Roast vegetables with chicken or lamb and Yorkshire pud Ham sandwich with cheese, grapes and cherry tomatoes
Not tried this yet but mini pizza with assorted toppings - mushroom, tomato, peppers, courgette, chicken/ham, pineapple etc - not all at once though .
Thankfully he will still let me feed him with a spoon but you could try thick soup with toast fingers. Dip the toast (or breadsticks) into the soup and use that instead of a spoon iyswim.
In terms of mess, I have two dogs that sit either side of the highchair and catch everything that goes over before it even hits the floor
DS is 15 months & has firmly decided that he will be feeding himself from now on! Until now he's had a combination of finger foods & something spoon-fed at each meal - e.g. vegetables as finger food & mash/flaked fish spoon-fed. He's starting to get the idea of using a spoon but quickly gets bored & starts waving it around & tipping his bowl on the floor. He absolutely refuses to eat if we try to spoon feed him, although does occasionally allow us to put food on the spoon for him to feed himself. There are some evenings when we need a quick meal without getting stressed. DH hates mess & seems convinced that all food put on the table must be eaten. We're working on his issues! We're sadly lacking in imagination when it comes to entirely finger suitable meals. There's only so many times we can feed him cheesy pasta without worrying about a lack of variation!