Maiden Voyage

Electrical usage by the pump and tongue jack are negligible because the operate on a very low duty cycle. Ditto for the fridge on propane because it has a very low current requirement. LED lights aren't bad, but the fans (bath, furnace, or other ones you might add) use quite a bit. As does the TV.

We used fans in the mid Atlantic and watched a movie in the evening, and consumed around 30-40 amp hours a day, so you will probably be less. Bear in mind that you don't want to bring lead acid batteris down below about 50% state of charge so a single 100 ah battery in your case might last about 2-3 days with no recharging.

I suggest you get a multimeter with clamp on DC current measurement capability. Clamp it around one of your battery cables and turn on one load device at a time. Record the current each item consumes. Then you can make up a table of current and expected daily hours of use. Multiply the two together for each item then sum for a total. A spreadsheet is handy for this. This way you will quickly get to know what is consuming electricity in your particular case and what you don't need to be concerned about.

As for portable solar that's a great way to start out. You can clip to the battery but you'll still need a charge controller and please install an inline fuse at the battery + terminal for safety.

Also if you are running more than a few feet (so you can place the module in a sunny spot) use some heavy gauge wire to keep the resistive voltage drop down. It's only a 12V circuit so voltage losses can be quite significant.

For a 100 watt solar module you can use 12 gauge wire for a 25 ft run, or 10 awg for a 50 ft run. You can use a 20 amp fuse for the 12 awg or a 30A for the 10 awg wire.

A 100 watt module will provide about 25-35 amp hours per day anywhere in the country on a sunny summer day if unshaded and oriented south at about 20 degrees tilt. This doesn't need to meet all your load demand, just extend your battery life while you are boondocking for a few days.

You can always add another solar module later if you find your consumption to be much higher. By getting a controller that can handle 2 modules now and choosing a heavier wire for your cable run you wouldn't need to change those later.

Propane lasts a good while, from what I can tell the fridge is pretty thrifty running on propane. I went  to a two-tank setup because of that  "one time" at the end of the season when  I forgot to check the level and  ran out. Some people have room in their tow vehicles  to carry a second tank, I don't. Tow tanks is more than enough for  a full season (May-October for me) of fairly frequent 3-4 day trips. So a single tank should be fine, perhaps check it evry few weeks, depending on how much you camp. I have a single std  deep cycle battery and use a 100 w Renogy portable solar panel to keep it topped  up, using the battery for fridge motor, water pump. lights, and furnace fan when needed. Its more than adequate  but we get lots of sun in Colorado. I did put a 20 ft cord on it so that I can move the panels around to keep them in the  sun.

I don't think AGMs are worth it money unless you just can't bring yourself to check your flooded battery water level every few weeks. Deep cycle flooded golf cart batteries tolerate cycling better which is important if you're boondocking. You can fit 2 6V GC2 size gold cart batteries (about 220 amp hours) in the rpod rack assuming you can tolerate the tongue weight (about 120 lbs for 2). If that's not acceptable then you can go with a Li battery but you will have substantial cost and work to do, as much for the charger and DC to DC converter for tow vehicle alternator charging than for the battery itself.

As for potable vs roof mount solar there are pros and cons either way.

Roof mount: more secure and easier setup but I'd you like camp in the shade then your performance will be poor, and you have holes in your roof.

Portable: less secure and more setupbut you can move the modules into the sun and you don't compromise the roof.

Either way, don't get so called flexible solar modules, get glass/aluminum frame. And get crystalline silicon modules, not thin film ones. You will need a solar charge controller too, a simple PWM one will do. Most have both Li, AGM, and flooded lead acid charge settings, but be sure the one you get has the settings you'll need for the batts you select.

When we travel, we usually have the fridge on 12V, but have never had an issue with the battery. Our (2015) F-150, and I assume any of the same or more recent vintage disconnects the 12V shortly after the ignition is off. So we switch to propane (or AC) shortly after we arrive at our destination.

Good first outing!  Have you considered  using propane for the fridge, we never use battery for it.