I believe that landscaping will solve many of your issues. Plant a tree to the right side of the porch and this will cut the long line of the roof in half and make it disappear.

The above suggestion is a good one, for sure. A few other thoughts.....once you put lighter siding on, the siding versus trim contrast will be less, thus not exaggerating the asymmetrical. I would paint out the attic vent above the porch in the linen color, as it draws attention to the roof peak. Painting the door a bright color, with porch furniture of an equal punch will draw the eye, as opposed to the roof line.

Alternatively, you could embrace the asymmetrical, and go for a "contemporary/artistic" look. Take off the porch. Build a wide deck that runs all the way across the front, with a really wide staircase up to it. Big colorful pots at the base of the deck stairs. Paint the door silver, like the roof. Do a table with a colored umbrella at the right hand side. Surround that window with arty pieces. Heck, since the roof is tin, you could go for those really large galvanized troughs for planters.

It's a really cute place, regardless, and doesn't look a THING like a double wide. :)

nwduck, has some great ideas. Love wide composite deck idea with a part roof pergola, also accentuating the asymmetrical. You could leave current porch and extend a pergola across to other end of porch. Embrace it's unique cuteness, let the house speak over added décor !