I can definitely sympathize, having an inconsistent work schedule and heavy travel isn’t conducive to structured training.
I’m a fairly new TR user, but have plenty of experience training and I’ve had success in a similar situation by focusing on sweetspot work. Maybe pick a few workouts that generally work for you, save as favorites and plug in whichever one, whenever you get the chance. Maybe a 1hr, 1.5, and 2hr option, or a low volume plan that only has 3 rides/week.
Right now I’m in the middle of a high volume build. I’ve got a variable work schedule, a wife, four kids, a farm, travel, and a 125mile one way commute. With six workouts per week I’m shuffling almost every day on a good week and skipping or substituting on occasion but trying to keep TSS on target. With a schedule like the one you have, that sound even less consistent, I wouldn’t be using this plan at all. Just hammering sweetpot whenever I get the chance and not stressing the details. You’ll get faster either way.