The question I would have is how many $300 loses can you withstand? It is your style of play, it is your money, but it reminds me of a movie I once saw, where a ship hit an iceberg and the announce went out to those remaining onboard, "This is the last lifeboat".
A significant factor influencing the playing time requirement is how long it takes just to get to the casino. My closest one is a 2¼-hour drive one way. I am therefore loathe to leave before getting at least that much time at the tables.
That is why I kind of like being close to a casino, choices are easier, and I really don't go any more because of that. But when I lived in San Diego, and drove 5-6 hours to Vegas, like you, I'm not turning around after a half hour, and driving back.....no matter how much I won in that half hour. I did try and implement some safeguards to avoid giving an early win back, but having credit at multiple casinos, that was a waste of effort.
I had no bankroll mgmt 30 years ago. I think I relayed this story in earlier threads... I lived in Huntington Beach, 10 minutes from Orange Cty airport in Costa Mesa. Pacific Southwest Airlines had $39 one way fares to Vegas. One time I flew out there and cabbed over to Barbary Coast. I planned to fly back later that night. I was way up after 45 minutes of craps play. After pressing my bets I had $100 flat with $1000 odds on most of the numbers. When the dice went out, I colored up and I called the airline and re-booked on the next flight out. I was in Vegas for about an hour. I also had trips that when I went up, I would put cash in an envelope and mail it home. I knew I would bust before the trip was over, and I wouldn't have a dime left. And it would happen. I would be sizing up the mailbox to see if I could get my letter back. Now I do $300 sessions. Like TD has mentioned, I let my winnings run, but when the luck peters out I call it a day. More often the $300 burns and I'm also done.