I did mine 2 months ago and used an agent in Vientiane he was great to deal with but comes with a cost of course he picked me up at the Nong Khia Bridge Laos side took me to my hotel and made sure he had all documents and pdf statements he needed to put in the application it took 4 full working days to do I can send his messenger ID to you in pm if you want with prices ect I recommend this guy speaks great English
just a bit of heads up for if you didn't know when you come back across the bridge after getting your visa there an inside office to the left of the immigration windows you have to go there to get your e visa stamped into your passport, I lined up at windows and wasted about 20 minutes for nothing
I traveled to the bridge by taxi from Udon then caught the bus across the bridge ,but yes there is a secure parking area before the bridge where you can pay a small fee to keep your car there
But I will be a hassle to get your bank account opened on a tourist visa I ended up traveling to Laos Vientiane to do my O.A.visa I used an agent there to do it for me because I'm a lazy person but you still have to stay in Laos took 4 days to process good luck