I have every ship in the game and despite my best efforts there are some of them I just can't find a use case for. Here are my humble suggestions on how to improve them. I think they fit the spirit of each ship and none are game-breaking:
Type 7: Tweak the ship's model to make it a medium ship. It's already nearly there.
Clipper: Give it a size 6 FSD.
Asp Scout: Give it size 5 thrusters and boost its agility.
Beluga: Add a size 7 optional internal slot.
Viper MKIV: Make the military optional slot a regular optional.
DB Scout: Upsize an optional internal to size 4 and add another small hardpoint.
Fed Dropship: Make the military internals normal slots.
Any other ideas?
