To me it seems like he would do fine with a V4L PV, I have heard of people filling up their Cartos with Juice and lasting them around 300 Puffs.
I am currently using a 510 and love it but I also have to deal with carts. What I did to alleviate this is use the BFM. I cut a strip of Blue foam and I basically drip 5 to 8 drops. that will last me about 20 to 30 puffs. If I am at work that is fine for my smoke break. Before I go outside I fill up and I am good.
I do run into problems when im in the car. Once I run out of Juice I have to pull over and refill which is a pain but I rather do that than drip and drive. For this reason I ordered a VK, this should make my drive home better, fresh Carto + USB PT should be enough to get me pass my 1 hour commute.
The Beauty about vaping is that there are so many good options that will cover your needs. I personally enjoy the research and trail and erro involved in it. That and the fact that I am prolonging my life is enough for me to stick it out and find what I need.