Okay, think I might bottle tomorrow. I am using 22 oz bottles. Given that 22 oz is more beer and more CO2 released during bottling than a regular 12 oz bottle, will the regular bottle filler leave enough space at the top of the bottle?
Try with water first. Assuming you have a standard filler, with a valve at the bottom, if you fill to the top and then remove the filler, the headspace will equal the volume occupied by the filler itself, because it will still be full of beer when you remove it. So, fill a bottle full (or nearly full) and then push the filler down to just touch the bottom (but don't open the valve). You will force some water out of the bottle, and when you remove the filler, the resulting level will be what you can expect if you do basically the same thing with beer. Adjust your stopping point when filling as needed to get it to come out right.
For a 22-oz bottle, you probably want about 1-1.5" of headspace. Doesn't have to be exact, as the amount of priming sugar will be by far the biggest influence on the ending carbonation level. Too much headspace can lead to oxidation, as the air won't all get absorbed in the fermentation process. Too little can lead to undercarbonation, but you have to leave almost no space for that to happen.
If you find your filler is leaving too much headspace, consider a filler with a top-positioned valve, such as the
Phil's Philler. When you release this filler, the beer in the tube stays in the bottle, and you can fill to just where you want it and it stays almost right there when you pull the tube. The only change is the volume displaced by the tube itself. Not cheap, but it's stainless steel and will last pretty much forever.