Britax G3 FF installation questions

I just installed a Britax Advocate G3 FF in a 2009 Honda Civic. Because my kids have been ERF for so long, this is my first FF installation. I think it's pretty good but had a few questions.

(1) Short tether path? -The headrest is raised, and I routed the tether through the legs of the headrest per instructions in the vehicle manual. This results in a very short tether path since the top tether is right behind the top of the back of the vehicle seat. It was difficult to tighten it completely. I eventually got it fairly tight, though not as tight as I usually like for installing the seat itself. This leaves the tether buckle sitting just to the side of the top of the seat. The vehicle manual says

"If the tether strap is too long and cannot be tightened firmly, find a route where the strap can be tightened securely."

I'm not sure how I would do that. Just wondering about anyone else's experience?

(2) Bypassing built-in lock-offs? - I first installed it with the seatbelt with one FF lock-off as per the manual, but didn't get a rock solid installation. I think it had a little more than an inch at the belt path. I then did it without the lock- off and locked the seat belt and got a tighter installation (though still not as rock solid as I get RF with LATCH.) The manual doesn't mention this, but I did find a blurb in FAQs on the Britax site where they said it was OK. Am I missing a reason why the built-in lock-off would be better?

(3) Head wings in front of vehicle head rest? There is a warning in the manual that says

"Some vehicle head restraints may obstruct the harness adjuster from reaching the highest position. If this is the case, you may need to raise or remove the vehicle head restraint. DO NOT force the child seat head restraint past the vehicle head restraint. Doing so could cause the child seat not to perform as intended."

They have a picture with an X of the extended head wings in front of the vehicle headrest. It seems that this would be an issue with most cars without removable headrests. At the moment it seems OK, but I'm concerned about having an issue when I raise the head wings and also in other cars with fixed headrests.

Thank you in advance for input!

I almost always remove headrests when installing forward facing seats. I've only had like two cars that had headrests that didn't interfere with the installation. I would remove yours and not worry about them. I also don't use the lock offs on my Britax convertibles forward facing, I can never get them installed as securely as I want that way. Britax does allow this.

There's no need to have a rock solid installation, only less than 1" movement at the belt path, but if the lockoffs cause issues, as possible said, go ahead and bypass.

With that v tether you don't want to go under the headrest. Go around instead. If the anchor is so close it went tighten all the way, remove as much slack as you can.

In most vehicles the headwings will go up, they were designed with forward leading head restraints in mind. They just don't want you to break them. But yeah a few may have problems and if so a different seat might be needed at that point/it will be outgrown earlier in that car.