Listen.....if parking it in the sun doesn't shrink the worst of the bubbles, then the best way to remove them is to aerate them properly.......
I've installed vinyl since the 70's when we did snow machines......Too much soap and it's gonna be a long haul usually......Water with about 1/3 rubbing alcohol and just a few drops of dishwashing liquid is the best wet formula for floating a decal.....the alcohol softens the adhesive and really gives you a great adhesion....the soap is for adjustment ease.
Some have used pins and needles to aerate a bubble (they leave a tiny "ring" at the puncture), but the best way is to use a BRAND NEW small size Exacto blade (standard cutting triangle)....These have an incredibly sharp point to work with........after pressing the bubble (at normal temp....NOT heated in the sun) with your thumb to pressurize it to the smallest size, carefully insert the very tip of that blade at the very EDGE of the bubble......then with a wet paper towel (wet with the solution mentioned), press out the remaining air. After the air is removed, press gently and repeatedly with your finger tip (if you have one, a felt half-round vinyl squee-gee is better). The wet paper towel will actually press a tiny bit of the solution inside the hole to help reset the adhesive.
After this process has been completed on any remaining bubbles, sunlight the car to complete the set.
If it's done properly, you'll need a magnifier to find where you've been.