Personally, I think any practice should be immersive. It should flavour 24 hours of your day - which why I think a retreat is great for ngondro as it's all you're doing - it can do its job and take hold of your mind. Interrupting it with an ordinary lay-person's life spoils that for me. I have no doubt that what you've mentioned is very productive and that I'd also find it productive.
You may think the interruptions of your lay life spoil it for you, and it is almost certainly the case that being able to live in retreat as long as you want would provide the optimal circumstances for palpable continuity, but there is always the infallibility of the accumulation of merit and wisdom to consider. If you are properly opening with refuge and bodhicitta, practicing with the least conceptual elaboration possible for you thus far, and sealing with dedication, you are definitely accumulating the two heaps. You are purifying obscurations. Once you've dedicated the merit, nothing can spoil that. You have to work with your circumstances. You don't have the circumstances for hermit life, or else your desire to live and practice in that context would have propelled you into that life. So you practice the best you can with the circumstances you have, and if it's feasible you work to bring about whatever circumstances you desire.
Basically, your logic that ngondro isn't a good fit for you because you have trouble allowing it to flavor your whole day is applicable to any other practice you could consider doing. If you can't immerse yourself in ngondro, you can't immerse yourself in any other practice either. However, the essence of ngondro - not least of which in the tradition you practice - is guru yoga. In post-session, you absolutely have the opportunity to consider everything you experience to be the 3 vajras of the lama, which really is identical to, and inseparable from, your own nature as the 3 vajras. And you can do that whether you're busy on the grind, having sex, eating, taking a dump, or doing a formal meditation session. How's that for 24 hr immersion?