Below are some tips that should help you get noticed and increase your chances of getting sponsored.
Come up with some footage. Try to make it as well rounded as possible i.e. street, park, vert. Don't make it too long (less than 5 minutes), and adding music is helpful so the people watching have a pleasant experience.
Tell them what you can offer them. Getting sponsored is not as much about what you'll get, but what you can give.
Show them you can be responsible. Show them a list of accomplishments like media coverage and contest results.
Get seen or let them know where you've skated. The more places you've been the better your chances. Create an online profile this shows them your out to be seen. Even if no one knows who you are, showing that your willing to travel to contests is critical.
Remember their main objective is to sell product. The more exposure you can promise them the better your odds of getting a sponsorship. Let them know that your willing to spread the word whatever it takes.
Hit up the small companies where your chances are better. Even though they can't give out as much they could use the advertising.
Lastly, suggest that your willing to start small such as handing out stickers at a local contest or demo. Heck let them know you do a demo for them at your local park.
One of the few companies out there making portable ramps is Lost & Found. I didn't get a sample ramp for review but I did do some research on their products. They have a wide variety of ramps ranging from a full 6' half pipe to portable mini launch ramps, rails and boxes. What makes Lost & Found different than other ramp companies? Besides the wide selection, they give a choice about what surface you want either Skatelite or RampX. Both of these surface materials are great for the outdoors especially in the wetter climates. Another cool feature is that the non-stationary ramps are easily movable due to the addition of rollers. Finally their products are modular so you can join them together to create cool obstacles. Unfortunately since I didn't get to personally check out any of the ramps I can't tell you anything about the craftsmanship, but from what I've read they thought of everything including tempered steel street edges and rust proof screws. If you want to find out more about what Lost & Found has to offer check out their site at Skateboardramps.com.