Yeah, this definitely depends on where you think you stand relative to your competition. If you'd literally have to sprint to hold onto the front for 5 miles, it sounds like you're punching above your belt. Which isn't necessarily a bad thing, but it does change your strategy, because you definitely don't want to try and follow. If you think you have a shot at a good finish, then it's worth burning a match early to avoid the funnel. And this takes A TON of practice. Even at the WC level, they get this wrong sometimes (looking at Nino and MvdP in Albstadt).
But, assuming you have, and are willing to burn, a match at the start, then the training specificity comes down to over/under type efforts. So, you could start VO2 work with a sprint that then settles above threshold, or you could do a threshold like interval that oscillates above and below LTHR (but not much below). Essentially you need to train your body to clear lactate buildup while still very near your threshold. Scratch that, you need to train your body *and mind* to do that.
To LMN's point, the start really shouldn't be a sprint for you. It'll be above threshold, but definitely not a sprint. Some people (and maybe you) might sprint right at the end to get the hole shot, but, it depends on where your fitness and skills are at whether you think that's a good idea for you.