Whatever you choose to pack inside the fish, will stay in there neatly and the fat of the bacon keeps everything nice and juicy. Here's what I did:
Ingredients (serves 2):
2 whole trouts
2 garlic cloves
8 slices/strips of bacon
2 tsp of dried Italian herbs
Salt & pepper
Preheat the oven to 400 F (200 C). Rinse the trout with water and pat dry with a paper towel. Open the body cavity of the fishes and sprinkle about a teaspoon of herbs in each fish. Cut the onion in half and then in thin slices. Stuff about half an onion in each fish (or as much as it can hold, without too much hanging outside the cavities). Slice the garlic as thin as possible and put on top of the onion. Sprinkle a little salt and pepper on top of the garlic/onion mix. Put about 4 slices of bacon on your work surface and place a trout on top. Wrap the bacon carefully around the cavity, to hold the stuffing, and press a little on the sides, so it will stick. Repeat with the other fish.
Put a little olive oil in a baking tray and carefully place the stuffed trouts in to it. Sprinkle a little salt and pepper on them and give it another good slush of olive oil. Place in the oven for about 35-40 minutes. Serve with a big salad. We ate this with a Greek salad with a little feta cheese.