Go and weigh your Jeep with and without overland gear. Full Stop.....
I have a '17 JKU Rubicon that has 100% stock suspension. It has a Gobi Roof Rack, Smittybilt Atlas Rear Bumper/Tire Carrier, Rugged Ridge XHD Bumper and Smittybilt X20 Winch. In all, an easy +400 lbs of exterior weight. Plus the added things on the inside like hard top liners, seat covers, whatever. All small weight additions but it all adds up.
It would be best to get the weights at each corner if you're not symmetrically loaded. Expect to add a small spacer to correct any lean as a result (and it is easier to add it before you get it all bolted back together).
At a minimum - weigh each axle.
Then select springs from there.
If the mfr cannot/will not advise springs based on these numbers, skip them - I don't care who they are or what sort of reputation they have on these forums.
Most tech support folks at the various mfrs may not want to divulge rates (which I think it BS, but that is another story) - but if you ask the questions correctly, you'll likely get an idea of which lifts will work for your weights.
From my experience, running slightly smaller tire than the 'max' tire for a given lift will allow more up travel - and greater comfort. Many of the shorter lift packages do little to improve up-travel, so bottoming/harshness while on rough terrain remains an issue. Bumpstops are usually driven by tire diameter/interference issues than by shock length/compression. Most Jeep lifts are geared towards trails/rocks and maximize down travel at the expense of uptravel.
An ideal Overland suspension would be around 50/50 or 40/60 (up/down) to improve comfort. Most Jeep lifts aren't even close to that. For example, AEV targets their suspensions towards overlanding and the standard 3.5" lift bumpstops are 3" front and rear. The 4.5" kit has 3" front with 4" rear stops. Their lifts net more than advertised and their shocks are known to be on the shorter side thereby yielding more uptravel. OME is going to say that their lifts are 2" due to Australian regulations...
I have a Frakenlift and run 2" bumps with 3" Synergy Springs F/R with a 3/4" front spacer to reduce rake (still slight rake to the front that all but disappears when loaded). I'm running Falcon 3.3 shocks designed for 3-4.5" lifts (no issues with bottoming out the shocks at full stuff). I'm also running SumoSpring progressive foam bumpers as a poor mans speedbump...I am happy with this setup and and my Jeep runs heavy - and is more heavily loaded when traveling. (IMHO, the Falcons are too heavily valved digressive - so if you go that route, get the 2DR spec shocks for your 4DR. I'll be doing this at some point in the future).
...Forgot to mention - I have been down this road (heavy & dealing with sag...). Do not underestimate the need for decent shocks. Do not under estimate shock fade - skip Rancho's or similar shock and go directly to an external res if you run heavy and like to drive at higher speeds.