First of all, much sympathy. How many of these have you tried?!
1.Set aside 3 days when you don't have to go out (you will need vast quantities of patience, dvds, wine and chocolate.)
When he's asleep, hide ALL his clothes.
Next morning open drawers etc and "Oh! Where have all your lovely clothes gone? They've gone away because you won't wear them. Oh what a shame."
2.Have you tried shopping for new and exciting clothes with him? Though hard to muster near orgasmic thrill at socks, I know.
3.What about ignoring him to the point that he's invisible when he's naked? Really, no food, drink, tv etc. Very mean but may be effective.
4.Try saying - "Mummy is very sad because you won't get dressed and she wants to go outside and go to the shops and the park/the bank and feed the ducks etc" Let him know you are sad and disappointed - children are people pleasers, this won't make him happy. If it comes to it, cry.
5.He's too young for some bribery, hence not giving a stuff - he needs to see it before it makes sense to him. ie - showing him the biscuit he can have when he's clothed may have more effect than telling him he can have a biscuit if he gets dressed. If he won't get dressed, you eat his biscuit.
These all make me sound very mean, but I feel like you are in 'Last resort' territory. Agree about not wanting him to be scared of you/anger thing. Asserting your physical strength over a child rarely a good thing imo, and I think constantly forcing him into clothes will make him angry with you. Not forcing him into clothes right thing to do, though blinking frustrating!
Good luck, Pruni.