Harbor Freight has a Central Pneumatic 12V
high volume air compressor (item 93186) pictured below currently on sale for $50 normally priced at $70. Costco has a similar looking pump - I ending up going for the one at HF.
This is a far more effective 12V
pump then you typically see at Target or Walmart for inflating pool toys, etc. It connects directly to your battery with spring battery clamps, and the instructions suggest you run your engine while the pump is in use. The provided 31' coiled hose easily reached my tires.
I tested the compressor by letting five pounds out of my truck rear tires and inflating again to 70. At first I found it awkward but soon realized you did not need to press and hold the connector to the valve stem; it is made to screw on to the stem's threads. Inflating from flat would probably take a while and may involve pausing to allow the pump to cool, but at least you won't have to maintain hand pressure on the valve.
For "top-off" the compressor worked great. The hose has a gauge at the connector end so you can easily check progress. The provided adapters can be used with various inflatables or sports balls, but unfortunately nothing fits a Boston valve such as I have on my inflatable kayak.
The pump comes in a blow-mold case and will be a part of my travel equipment.
Why didn't I get the Costco pump? I trust Costco's quality more than HF, but the Costco pump had a shorter hose and the gauge was mounted on the pump, making it hard to see when you are 20' away at your tires. I think at the sale price the HF pump is a better buy and likely easier to use.