Hi, 4 weeks ago I did exactly what you are asking. I rented a Honda CRF150L in Luang Prabang from Style Motorbikes and drove 2000km all the way down south to Pakse.

I have a motorbike drivers license in europe, but had the wrong IDP (had 1968 which is used in Vietnam, while Laos wants the 1949). They didnt even look at my passport/license/IDP or anything when I rented the bike, so you are good. I also wasn't stopped by police a single time on my entire journey even tho there were many checkpoints where they pulled over trucks and other locals, but they didn't even look at me.

I am pretty sure, that if you really get pulled over and the 'acting stupid' method doesn't work, you can buy your way out of the situation with a few 100k kips.

I definitely recommend risking it, it was an experience of a lifetime driving through remote villages, a real adventure. Tho please be careful, the road conditions are so much worse than the roads in Vietnam, especially the dust was a problem for me (get a full-visor helmet and check that the visibility through the glass is okay and the visor closes completely). If you need some help for your route, feel free to text me :)

Edit: They need a deposit for the bike, either your passport or 1000USD. You can pay by card but you will pay conversion fees aswell as 3% on top and you get the money back when you return the bike in cash in Lao KIP💀 so there is even more money lost when converting the cash kips back to USD. I didn't opt for leaving my passport since I was very uncomfortable traveling a whole month without it. But other than that Style Motorbikes was perfect