Seriously, listen to yourself...
"If he keeps the dope to himself I will be able to do it."
A sensible person who's serious about recovery would MAKE SURE that they are NOT THERE for such a temptation. You'd send a friend to meet him if you had to, but first you'd just insist he drops the car off himself (rental places DON'T pay attention to who drops off a car, btw, so that excuse is gonna be BULLS**T, I'm warning you in advance My Fellow Drug Addict - and I use that term with affection
)
See how that works. The fact that you CARE about what 'the man' thinks going forward, and the fact that you are all set to do something totally DUMB like risk meeting him when you know he could toss dope your way constitute SERIOUSLY flawed reasoning for someone who is remotely concerned with getting clean.
This is why I tell people that they cannot get themselves sober once they are addicts. The addictive mind is too powerful, and you must learn COMPLETELY new ways of thinking and acting and they take a lot of work and a VERY high level of motivation to accomplish. Doesn't sound like you're there yet based on the choices you're pondering and the fact that you don't see to be on your way to the earlier-promised NA meeting...