Underground soil pipe runs, when fitted properly, are extremely reliable TBH. Gone are the issues with minor heave or settlement cracking clay pipes, and then the nightmare of roots filling the pipe at that break, so imo if there's the means to go under and you can keep to straight or relatively straight runs then I'd really not worry about it.
I've seen so many adverse runs ( which have been functioning without issue for decades ) to really worry about runs ( installed according to current regs ) to be panicked by running 'under slab'.
The above pic with the end of line rodding points is an excellent solution imo, and the real point to make here is about doing the job right rather than where. .