Heat oven or BBQ. Tightly wrap each posh dog with a strip of bacon until most of the posh dog is covered. Transfer posh dogs to foil-lined baking sheet.
If using jalapeños, place them skin-side down on a separate foil-lined baking sheet and lightly drizzle with oil.
Roast jalapeños until skin starts to blister, about 25 minutes.
Roast posh dogs until bacon is browned and starts to ripple, about 30 minutes.
Meanwhile, heat 1 tablespoon oil in a large skillet over medium-high.
Add the red onion and cook, stirring frequently, until it begins to brown and shrinks by half, about 10 minutes.
Stir in peppers and the remaining 1 tablespoon oil; season to taste with salt.
Remove from heat when onions are caramelized and peppers are soft, about 20 minutes.