By the sounds of it, you could be a little too hard on the vehicle. A little more driver sympathy may be required. I have not heard of this issue before.
What has been changed on the vehicle from factory?
Did you vacuum and clean the interior at the same time? If you did, the battery could have flattened due to the interior lights being on for long periods.
The fast clicking is a sign that the battery charge is too low to engage the starter.
If you had no issues before and did after, there is a good chance that could be the issue. If you do need new injectors, look into the Baileys Diesel Group ones.
I can't recall a lot of lifted builds on here, you may also benefit from a more offroad/4x4 based forum as they cater more specifically to that market.