Lots of questions for a single post. But,
1. WDH.
It's your $$$ and effort, so would you rather save $$$ and spend time transferring the WDH setup, or get a new/used WDH? Craigslist, or call your local RV shops for used. To me, if you can find the same model WDH, you get it, and it will have the arms and a-frame devices, so you can use the same WD drawbar.
But, if you need sway control (many folks prefer it with TT), just get a completely different unit. Again, sources for used units.
2. Power.
With a family, your first task is to train everyone to conserve energy. LED lights help tremendously. Just turn off what you are not using at any moment. Turn off water pump if no one is going to be using water in the next 15 minutes, as it may cycle periodically. Furnace will be your largest energy sponge. If you are warm enough without furnace, you should be good for at least 3 days on a single deep-cycle battery, and prudent use of electricity. Two batteries are better than one. Don't use an inverter, as they also use lots of juice. Don't watch videos, etc, unless you are going to be plugged-in. I suggest two 200w solar panels, which will do wonders for recharging your batteries. I have not used a genny, and we have camped up to 9 nights without being short on battery (200w solar, 2 12v deep-cycle batteries).
3. Propane.
We have not gone through 20# propane during any summer campout, even using the furnace. I cook on a 3-burner stove, propane water heater, and run fridge on propane. You should be fine for a week with 40# available. Longer, use the 10# 1st, then fill it while on the 30#. Or, use the 30# until empty, then run on 10# just long enough to get the 30# filled. Refill 10# after second use after emptying the 30#, if you use it for two or 3 days. Normally a minimum charge to fill a tank, so you don't want to only get 2# an pay full-boat.
4. Waste tanks.
Black is the pooper, gray is kitchen and shower. Don't let black get full, as you have already experienced the fallout. When emptying at a dump (there are smartphone apps for locating dump stations), empty black first, so your gray rinses the system when you empty it. Also, don't keep the black too empty, as you want lots of liquid to flush out the solids. Use a good tank chemical, though, and your solids should liquify on the way to a dump. Don't scrimp on the chemical.
5. Camp Grounds.
Depends on what you want, and how much you are willing to pay. National Forest campgrounds are generally about $20/night, State Parks (out west) are normally a little less, private and KOA campgrounds are $35 - $50/night, depending on many factors. Your signature doesn't say where you are (don't recognize the town), so can't say what your campground availability is. Recreation.gov is a listing of Federal and State campgrounds for reservations. They only list campgrounds with reservations available, so it is not complete. Also, if you use GoogleMaps, or GoogleEarth, and turn on Parks>National Forest campgrounds (forget the absolute path), it will show you where the National Forest campgrounds are. Turn on more options, and it will show you State Parks, etc. Again, not knowing where you are, maybe those aren't ideal for your area.
6. Waysides.
While many say they stay in parking lots, I would find a campground, as they are generally more secure. I hate spending money, but to me, $45 for a KOA or private campground is better than a parking lot. I plan my trips (live out west) to overnight at State Parks along the way, as there are enough along I-70 to get me a decent travel distance.
Lots more to learn. Forget your CDL experience, as a TT is different, along with different needs. Your CDL likely made you more aware of driving situations ahead, which is good. Also, more aware of street widths, which is also good. Other than that, can't say there is a great crossover in skills. Your big trailer and tractor drive differently than a pickup with a TT. Not saying which is "bad", as neither is. They are just different, and expecting a TT to behave like your big rig could be a bad idea.
Safe travels, and enjoy the experience!!!
2017.5 Lance 1995
2017 F150 EcoBoost, Max Tow
Most camping off-road