The hard truth is that you're going to need to start shooting those lower numbers. We say "no shot" under 200 for people who are brand new but even then, we don't really mean "no shot" most of the time.
It's more of a "stall point"....at first, if you get a number under 200, you should stall, don't feed and test again in 20-30 minutes to see if the number goes up without the influence of food. That's usually a pretty good sign that the last shot is wearing off and it's OK to go ahead and shoot.
But once you've got a little experience, that "stall point" drops to 150, so anything over 150, you'd give the scheduled dose. If under 150, you'd stall, don't feed and retest in 20-30 minutes.
Eventually, you learn to shoot lower and lower numbers. On SLGS, you work your way to shooting anything over 90.
Of course the days you do this for the first time should be days when you can keep a closer eye on him and get at least 1 mid-cycle test in.
Lantus doesn't work as well on a sliding scale as some other insulins, but it has been done.