BIAB Pliny The Elder Clone

I am currently boiling the all grain clone from the AHA link: https://www.homebrewersassociation.org/attachments/0000/6351/doubleIPA.pdf

I tried to do this with the BIAB technique. I filled up my kettle with 8 gallons and got the water to strike temp then added the bag full of crushed grain. I mashed around 149-151 for 75 minutes. I then removed the grain and got the water up to 170. I placed the grain bag back in to sparge for 10 minutes. I removed the bag and go out what I could from the grain to add to the wort. Topped up the kettle to 8 gallons per the recipe and my pre boil gravity was 1.044

I know this is pretty low efficiency at around 66% but I am adding 1 lb of corn sugar towards the end of the boil. Does this change my efficiency at all?

1. Next time crush the grain tighter

2.>>I know this is pretty low efficiency at around 66% but I am adding 1 lb of corn sugar towards the end of the boil. Does this change my efficiency at all?

It doensn't affect your efficiency, but it certainly affects the OG

If you boiled from 8-->5 that would have given you an og of around 1.070, and add in the 1lb of sugar, actually puts you ahead of the 1.072 desired. So if you only boiled to lets say 5.5 to 6 gallons you probably ended up pretty spot on

What did you top off the kettle with? water or wort?

I'm wondering what your pre boil/POST MASH gravity is. I'm willing to be it is near 1.050 giving you higher efficiency. Also is it 1.044 temp corrected? Or do you save it and measure it around 60?

I just did a Pliny BIAB (not a kit) and I've found that stirring the mash every 15 minutes or so really helps with efficiency. I do a bit of a bag squeeze and never have problems with efficiency. But, almost every time that I check pre-boil gravity, it's lower than what Beersmith tells me it should be but I end up hitting my numbers in the end.
If you adjusted for the temperature, it seems you're doing what you should.