Do I actually need a second portable charger, or is the one that came with the car enough to keep in the trunk 'just in case'?

Mine has never come out of the cargo area on a trip. Every time I've been tight getting to or from my mom's the answer was a fast charger - 120V doesn't do much when you're 20 miles short and want to get there tonight.

I'd keep the free one and not think about it much. We've done a lot of road trip miles and the portable cord has basically been ballast. If I'm 10% short, a few % from somebody's outlet doesn't fix anything. I still end up at a fast charger, and the time spent finding an outlet, asking, and running a cord out could have been spent at the DCFC getting more than that. The only time I could see a nicer 240V portable paying off is if you stay somewhere a lot that already has a dryer or 14-50 outlet where you can actually park near it. Even then... running a cord across the in-laws' garage while everyone's eating dinner gets old fast.

What would actually ruin a trip is a dead DC station on a stretch where it's the only one, and a fancier portable doesn't fix that either. I had one route where if the EA site was down we'd have been on L1 for like 36 hours. A 32A cord doesn't help at a Super 8 with one outlet behind the nightstand

Ok good, that's kind of what I suspected. Part of the reason I was even asking is the guy who installed the wallbox tried pretty hard to also sell me a portable 40A unit "for trips", and I couldn't figure out when I'd ever use it.

What was he asking for it?

Installers do that a lot. The quote for my panel work came with a charger bundle I didn't ask for either.

I think it was somewhere around 400-450 on top of the install. I didn't look that closely because I'd already decided no by then.

A 40A portable also needs a 14-50 on a 50A circuit to actually pull 40A, so unless every place you visit has one it's going to be running on whatever adapter you have, which on a 120V outlet is the same 12A as the free one. So what you'd really be buying is a second 40A cord that sits in the trunk plugged into nothing. I'd guess he was hoping to put a receptacle in somewhere too, that's usually where the upsell ends up going

We have three EVs and I think there are three of the stock cords sitting in a bin in the garage. None of them have been on a trip in years.