Assuming it it a concrete tube with an unknown amount of rebar, the amount of directional change and at what distance is the question.
You may be able to succeed with a single 2.4 ap. You mentioned placing up to 3 aps… so you can run power some how, on the interior of the tube? I take it this isn’t a bypass but an inspection tunnel?
If you only have 1 shot to do it, over saturate, otherwise, install and test to verify performance.
If you have the ability to install cable in the tunnel you could adopt a leaky cable system. I don’t have direct experience with this, but I did do some work for a mining company that used it extensively.