Split rims used to be called widowmakers.....
True... sort of. Widowmakers were split rims. Split rims are not widowmakers. Widowmakers were a different design no longer made (for a few decades now - I could be wrong). Most semi trucks now use Bud wheels (tubeless) but at least around here a lot of aggregate haulers (gravel trucks etc.) use 22,24" split rims. I have repaired more split rim and tubless flats than I'd like to remember. Tubeless is easier and less work but both can be done on the side of the road. Hell, tubeless can be done without removing the tire from the truck if its an outside tire. I'm talking semi tires here but the same goes for car tires. Tubeless car tires are obviously easier with a mounting machine but can be done with two bars and some lube.
So to the OP question - really its personal preference based on your past experience and future expectaions.
Personally I have both the original 16" splits and a set of 15" tubeless with the cap clips. Eventually I plan to use both with one being designated DD and the other offroad.
As for repairing a spilt rim flat... Here is how I do it. I accept no responsiblity for your actions.
1- remove and air down
ALL THE WAY TO ZERO PSI
2- lay the tire on the ground ring side up
3- put your weight on the side wall to push it down and gain some space between the bead and the ring. You may have to put something under the wheel to help.
4- use one prybar to push the ring end with a notch (if present) down by sticking the prybar between the ring ends and... prying
5- while holding that one end of the ring down... stick the other prybar in the notch (or between the depressed end of the ring and the wheel if no notch is present) and pry the end of the ring up and over the shoulder and off the wheel - hold that second prybar in place to stop the ring from snapping back down.
6- Now take the first prybar and keep following the ring around and prying it off - pry between the rim and ring - at some point about half way around the ring will become loose.
Thats the easy and safe-ish part. Just keep a hold on the prybars or they will smack you in the shins, face or worse

.
7- Slide the rim out of the tire by standing it up and pushing it out - carefull of the tube stem - fold and push it through the rim.
Inspect the rim and ring for cracks and nicks - particularly the mating surfaces of the ring and rim locking area. Find cracks and cut the rim in half with a torch - same for the ring. Small nicks can be filed off. Wire brush the mating surfaces and generally clean up the steel parts.
8- Fix the puncture by gluing a patch on the tube AND the inside of the tire. Oh... and remove the offending object. I used to keep them - kind of a trophy. I've pulled nails, screws, sparkplugs, scrap metal, screwdrivers and my favorite...... pennies! out of tires. Yes, pennies. Several times.

Usually only half the penny is left.
9- reassemble the tube, liner and tire. Slip the rim back in and lie it down with the ring side up. Set the ring on the rim and using your foot push one end down and under the locking shoulder of the rim. Then with another foot work your way around and snap the ring fully into the locking shoulder.
10- Take a hammer and tap around the inside of the rim lightly to sort of shake and vibrate the assembly to ensure the ring is seated.
11- Use a cage or more likely a chain. Wrap the chain around the tire and rim in two or three places. Make sure it is hooked and closed fairly tight.
12- Add just 5psi to the assembly and get that hammer again. Tap around the inside of the rim again to ensure the ring is seated. Do not proceed until you are happy with the way it looks (i.e. - it won't blow your head off)
13- Air up to the recommended pressure. Don't stand over the tire and read the DOT crap while doing it. Get a clip on extended air filling gauge. You may hear a pop or other noises as the bead seats itself as the pressure builds. The truck tires I worked on go to 100-110psi but that is their designed operating pressure. Remove the chain and get back on the trail.
If after reading the above you don't feel comfortable about it get someone else to do it. Find a buddy that has done it before and watch and learn. Worst case call a heavy equipment or semi tire shop - they still use them and should be able to help you. Your corner Goodyear dealer won't help you.