Manufactures who install residential fridge's only install two batteries. I don't know what size of inverter they use but whatever Heartland installs in their units is not big enough. I don't think it is a 2000 watt one however.
A few years back I towed a boat behind my 5er. I kept breaking the springs on the 5er. I ended up adding a leaf to the springs and solved the problem. I guess it was close to the max and the extra weight on the rear put it over. I never weighed the rig but the boat and boat trailer weighed 3050 pounds.
I'm not sure about Dodge, but you may not have a choice when ordering the truck. I would think the 3.43 would work but it may only come with the 3.73. You should not need the 4.11. This option may only be available with gas engines.
My recliners are in the back of the unit and I must turn them sideways so the slides will clear them. There are straps fastened to the floor and I bring them across the chairs to keep them in place. If they moved one inch they would interfere with opening the slides. My old unit had more room and I never secured them and they didn't move much.
Many years of trailering and have never had a bearing failure on the road. This includes RV's and boat trailers. I don't carry a spare and they are readily available if I need one. Every auto parts store will have them.
It would take a long time to fill it with a short hose and funnel. I have always been able to find a fresh water supply with a threaded bib where I could attach a hose. Most dump stations have a potable water supply close by however it usually involves driving away from the dump station. Like you, I would prefer a gravity fill like the older ones but it seems that those days are gone. Most manufacturers are going to the universal docking station with the pressure fill like you have.