Is the easiest way to get access to everything... is a 'mod' I had wanted to to for mine after realizing how much work it would be to do something as simple as a clutch.. ! Need to check if I jack the engine up and remove the mounts whether the block will drop through the rails.. it may work with a bit of wrestling. Would then need to mod the rear gearbox mount to make it a bolt on, rather than welded bracket and it would be 'possible' !!
Is great to watch how you have tackled these issues Wil.. good to learn from your experience and consider whats achievable with a bit more know how...
PS.. 5x for your driveline calcs is a reasonable safety factor to account for shock loading..