As luck would have it, I had purchased a set of Hi Lift springs YEARS ago for a project, but never used them! Sure enough, the outer holes of the springs line up well with two of the holes of the TLT, which is great. However, I assumed I would need to drill through the axle housing to secure the springs to the housing, but I just threaded in some screws and was surprised to feel how strong it felt!
Could it really be this easy? These are the longest screws I felt comfortable using. I think the screw was close to bottoming out in the hole.
The screws are pretty short, but the spring really feels secure in there! If this holds, I would just need to slightly space out the leaf spring hangers and shackles from the chassis since the TLT's spring mounts are a little wider tha than the stock axle.