All the great comments start out with "In my opinion" and "According to what they say" and "My brothers cousins first wife did this".
Search Wagon Gear for the top of the line lid that includes all the structure and rigidity necessary to open up the tailgate area to accept your requirements. Kevin is a genius when it comes to acquiring space and maximizing cubbies and dead air in the 80 series. You could easily mask the opening by attaching your carpet to it.
"Individuals in the past" have noted that tailgate storage is a great place for light weight recovery gear, webbing, snatch straps, and soft fluffy things. The rationale for light weight things related to their significant other not being able to close the heavy tailgate or fearing that it would crush them when they open it. I have heard talk of a few who have discussed how to integrate the slow opening contraption on some of the full size toyota pickup tailgates to address managing the weight.
"I have also seen pictures on MUD" that showed a license plate delete (opening up the tailgate interior by pushing out where the license plate is located. The delete would really open up the interior of the tailgate to provide the necessary room for any "tool" of your choosing.
It all sounds well and good until you factor in the a$$h@ts who tailgate a 6,000 lb marvel of engineering such as the Land Cruiser. This point caused me to personally rethink putting anything of value into the tailgate. Yes, it is tacti-cool but a$$h@ts who rear end me won't give a rip about what's behind the curtain.
I have determined that if I ever decide to purchase a weapon

, I would use the quarter panel area for a collapsible battle hardened rifle, using L-channel and quick fists. Moisture lives in my truck and the less stuff to absorb it the better. I've never done it but I think it would work quite nicely.
There was also a really well done hatch on a GMC Yukon I saw years ago that had the top covering the rear storage area. Open it up and there was a full array of tools available to a discerning operator.