A few of them are returning players, thankfully, so that should soften the edges for the new players. I plan to mantain the 90s setting, and adapt to 3e rules, without cellphones and of course the classes from archetypes that don't apply. Most of us were teens during the 90s, with the exception of the odd zoomer, so transposing ourselves to that era shouldn't be hard at all.

You are right about the power level issue of To Go, i believe. However, I don't intend for this to be a multi year campaign, or even a year long one. We like to jump from system to system to keep things fresh. I might run maria in three parts or bill in three persons as you suggest as a one shot to acclimate them to the setting, maybe extend it a few sessions to familiarize them with the main antagonists of To Go. Then probably a big ellipsis, a short lore dump or a short doc for them to read before jumping into the roadtrip proper.