I use the cargobob for the sell missions. I have the warehouse at Elysian Island and there's a spawn place really nearby (at Merryweathers port). Mostly the delivering spot is in the Chumash area, so mostly I'm flying above water, following the coast. No damages to the car and a lot of fun flying the cargobob..
This. Bob is right there at the Merrywether dock! Get the car out, park in the lot, call Buzzie, get the Bob (no rush there or you will be forced to shoot that goons), pick up the car.
Further: don't ditch the Bob! Land it near warehouse, there are nice spots. Using this method you will be able to lift both when sourcing and when selling too without calling Bob several times.
Elysian island pro-tip: use the railways when sourcing public without Bob. You can literally go around the map without any ground interference right from the warehouse exit!
I don't stop and fight the waves, waste of time really. The trick is to just blow by the first wave of Sultans then stay just far enough ahead of them that they don't despawn. Get far enough ahead that they drop off the radar then slow down some, once you see them reappear behind you speed up. Keep doing that until you get to the drop-off. I average less than $1,000 per car in damages and that's just from the bullets that hit when I first pass the NPCs. A decent driver will not get any damage from collisions if you keep a close eye on the traffic, especially if you take your time to keep the NPCs at a reasonable distance.
And actually this lad right here, you deserve single malt for promoting right way of thinking. If you can drive, you won't lose over 2-3k per delivery and sometimes it's quite funny to drive under pressure!
Okay, it's about time we should bust some myths about Bob, so here you go:
— Hook won't glitch in solo lobbies. I got 4 mil in sales with Bob now, no unhooking so far. Yes, there are reports that it can happen in solo too, but it's inadequately rare compared to network hiccups. So it's lag-related, probably. Solo you're mostly safe;
— Roosevelt Valor is the easiest car to pick up. Try it if you don't believe me. Struggling with Bob? Use Roosevelt. Straight big roof is the best;
— You can outrun choppers with it. Just gain altitude right after pickup. That is the reason I don't like that platform near Zancudo.
Oh, and sourcing wise: use 80% strategy and blow up the car in case you don't like the mission. Especially, that platform one near Zancudo. Not worth it, mostly, but sometimes you can snipe guys easily. In this case to avoid source times, just go the warehouse and sell another top tier and source later.