Yours is actually a common situation, aka real life. I have been there. A couple of suggestions. Because you are training-time-constrained, the goal is efficiency. How can you most efficiently use your available time? During the week, I recommend long L4 segments with no more than 5min warmup and 5min cooldown. If you have an hour, warm up for 5mins, do a 50min L4 and cool down for 5mins. If you have more than an hour, break up the L4 into two parts with a 5min recovery duration (e.g., if you have 75mins, do 2x30min L4s). Also, if you have the available space and budget, I recommend using a trainer during the week. Trainer rides are incredibly efficient compared with road rides. I can go from street clothes to 60min trainer ride to street clothes in 90mins. And, trainer rides aren't limited to sunrise to sunset.