"The_Dude" you are on the correct track to take into account the weight being added to the vehicle.
This is not so critical for the weekend warrior, but true over-landers this is more important.
There are many variables when you change the configuration the a vehicle. Where is the weight added (high or low, front or back). This is adding the weight of the gear and add-ons make handling of the vehicle change.
One thing many people over look is the tires when they keep adding weight. Granted many people get a larger tire then the stock. These may not be able to carry the additional weight (they could be a B,C or D rated tire when they should have been a E rated tire for the added weight. The larger tires are added weight. Granted they are added above the springs, but they change the configuration of the vehicle manufactures engineering of the vehicle. Is the drive train up to the added stress? Are the braking abilities now up to the job?
The suspension is still important, but only a part of the equation. Soft springs and the shocks will take a beating as they try and control the added weight. The weak shocks will add additional body roll and weight transfer. Both of these can cause loss of control at highway speeds.
Many overlanding people think that they have to have everything sold with the overlanding look. This a marking ploy by manufactures to sell their product. Good example; High lifting jack (farm jack), they have the tough look, but where would you use it on your vehicle? Where will you carry it? With some of the accessories you could do some of the uses it can do, but lifting your vehicle is very limited with one of them. The jack and accessories weight about 100 pounds.
Good luck with your build.