If I was jumpstart cars all days for living (actual a dream post retirement job for excuse to crisis around on someone else gas) I would get 2 Gooloo GP4000, and 40-ft jumper cable, and maybe a JNC 1224. The JNC1224 packs two normal JNC660 into one package but it is heavy. I would most likely rigged up some sort of inverter and run an extension cable to attempt to recharge the customers’ cars if I want to make sure they can restart themselves once I am gone. We’re talking Cadillac service now but OP is also a battery seller so I am assuming there is some potential serious conflict of interest there.
Time is money when we’re talking about Americans actually having to do work, especially when places like AAA don’t necessarily pay much for service calls such as jumpstarting. So a decent lithium jump pack to backup a standard jump pack is ideal. I had seen road side repair guys let their vehicles idle while spending 15-30 mins on a jump job and I always shake my head. They should turn off their vehicle unless they plan to use it ti jump the car. This should be a quick 5 mins job and 5 more mins to let the customer car recharge their own battery then get them to shut the car off for 1 minute and restart themselves. If they can’t and the battery reads less than 12 volt, they probably should be advised to go to auto part stores for a second check and battery replacement. If the road side derive people also sell battery, I can’t see how much premium they can charge; $50 extra over what AAP or AZ charges? Those places already have about $50 premium over Wally because of all the free checks they do all days. That is why Costco battery is the cheapest, they don’t do checks and they don’t install battery. Thst free install from AAP and AZ are already in the price and I would be nervous about letting Wally ward install battery.