[Demi Lovato's Heroin Spoon]

Gonna re-re-repost this because I like the maneuverability of the jetpack. This idea never picks up traction, but anytime this comes up, I'll keep suggesting it. The second link has a damage multiplier function, but that can be easily negated and removed. All of these options are probably gonna make b-hoppers cranky.

I've looked all over the Valve developer wiki and Garry's Mod wiki for a possible solution, but I don't believe it's entirely possible with the engine Garry's Mod works with. If you were to match the players hull with the model compensated with the jetpack boost, there'd be a severe issue when trying to get over things, and I think even under. It would feel terrible for those even who don't crouch jump.

However, I've found a possible fix on GitHub, but this is one I personally don't know if I enjoy compared to other potential fixes. The basic idea is that after a crouch jump, once you hit the ground, you're locked to the ground for a few seconds to prevent jump spamming. You can probably see the issue with this. 
 
  This is the GitHub lua code for it: GitHub

  A few other options:
 
 1) Lower the upward velocity given of the jumppack and alternate for more of a "safe-fall" option which would be encouraged as a simple hover rather than upward boost.

 2) Crouch jumping makes your weapon extremely inaccurate- the worst option would be to 'jam' your weapon from firing when hovered. 
    
 3) You can no longer crouch jump for x seconds after shooting your weapon. 
          - You can crouch, but not jump and vice versa.

 4) A function that prevents crouch jump spam by locking the player for a selected number of seconds after consecutive jumps.
          - After x jumps you're prevented from jumping for x seconds.

 5) Get rid of the jumppack.

 I think one, three, and four are the best options.

After digging through the FacePunch archives, I've also found this GitHub. It's another player mode code to prevent jump + crouch spamming.