Please don't throw out the idea of meeting PS for private sessions at AVN without some direction on how not to do it.
DO NOT ask a PS on the show floor to meet you in private!
1. Prostitution in the city is illegal. You will be promptly tossed out of the show and the venue on your ass.
2. The fact that PS escort is perhaps the worst kept secret in the industry. But it's never discussed at the show, in a booth, or directly with the "talent," producers, etc.
Instead: Do your research in advance to ensure your desired PS will be at the show. If she has an active escort ad, contact her with the ad info and let her know what you want and where you will be staying. If she doesn't have an ad, try to find her personal email (never her modelling agency email) and let her know you're interested in meeting while in Vegas. If you can't find a personal email address, try to send a vague DM through Twitter/X asking if she is available to meet - but like any inquiry with an escort, no mention of sex or P4P. Twitter does read DM's.
Last resort: If you were not able to contact her in advance, you might be able to chat her up at one of the hotel bars. Usually there will be one bar located near the entrance to the show that many of the industry folks use after the show closes for the day. If you can, sit near her and make small talk. If you feel the vibe is good, you can make a suggestion about meeting her later for a drink, or dinner, or...
And as the OP mentioned, sign up for a TTS account in advance (search "talent testing services"). Then go to their lab no more than 4 days before you plan on meeting your PS. One, maybe 2 days is preferred if the location you use provides same-day or next-day results by text. Once you get your results, you can show her the result report or let her scan the QR code with her phone.
Life is good
The Cat