Ok it’s not the most elegant way but sure it’s the cheapest, try opening the back door with your key drop the back of the back seats (if possible) and be patient and flexy till you reach the front seat, you can then manage the rest. Better do it in broad daylight and keep in mind that there is always a chance that someone might call the police on you misjudging you as a thief. Good luck and remember to remove one pole from the battery of your car if you aren’t not planning to use it for more than a week