Baylor, you, the OP, and everyone else on this board know how very VERY strongly I feel about RFing. But after being in the same(ish) vehicle this weekend, turning the littlest RF in her MR is going to cause the backs on the HBB not to fit. If they do go back to the backlesses, the story changes, but with the seats she has at the moment that's the best setup she's going to get.
It's not what I would choose, it's not what you would choose, but my job (as a tech) is to get those kids "leaving" safer than they "arrived." Arguing about how to get the safest setup, which is outside the parameters that the parent has set, is only going to drive the parent away and afford her no assistance in determining a safer setup for her kids.
L-P, a few questions... 1) isn't that gap just due to the curve of the MR's back? It's not flat, so it's not going to end up perfectly flush.
2) How do they sleep in the Literiders? If they have headslump issues there, too, I really felt pretty comfortable with the Montereys, and your backseat looks less contoured, so they should fit better overall. Recent Diono drama aside, my kids sleep amazingly well in their Montereys and there are a few in swap for reasonable prices at the moment. I would try one locally before purchasing if possible (do you live near a member that might have them?)
3) Is the gap behind the Big Kids behind the backrest, or behind the "neck" area? Behind the "neck" is normal and expected, we are just trying to get the backrest flush.
I thought I had another question for you but I can't remember it now, so I will follow up later if I remember it lol.
1- The gap is because the MR shape but the vehicle seats are so squishy that Im sure if you tried you could push it back further and have even more of the back of the MR touching the vehicle seat. Either way though it was a great rock solid install. Didnt move at all in either direction
2- The kids sleep nicely in the LRs. They sit back deeply and stay almost perfectly straight. When they do shift around its not enough to put them out of position. The have been using the LR's since the end of July so they are used to them. I honestly dont think Ive had to wake either one up to have them straighten up in their seats.
3- With the HBB the gap is just under the wings and above the backrest.