That's exactly the plan, it is surprising how physically small the heat exchanger can be, I worked with an application engineer from GEA and then Brazetek, and both came up with very close conclusions so I made my choice on a Brazetek unit as the footprint fit the application better.
I originally had a 8 gallon Isotherm hot water tank going in and the space requirements of the Espar, heat exchanger, heating radiator, fit in less space than the hot water tank, so it freed up a good chunk of space. All of the listed components are actually in line with each other and fit nice and tight.
For weight savings I lose the 42 pounds for the water tank, plus 30 litters of water which weighs 66 lbs, the heat exchanger weighs 6 pounds so theoretically I will lose 102 pounds.
And according to the engineers, one of the guys I dealt with had some good experience with Espar and Webasto heat sources, if everything is sized right 5 minutes will have water at 90 celsius. This system can be tied into a vehicle heating loop as well for permanent mount bodies. Gary's experience was also a strong contributing factor to the redesign, same heater, same application, similar size of camper body, similar panel system, and real world use by a highly respected explorer made the decision easier.
As for the cook top Ward, we usually do almost everything outside, even though we have the inside equipment we are usually doing things on the barbecue and an outside cooktop. We are AC hogs, my wife uses an electric toaster and an electric coffee maker inside the 650, and this camper will actually have more amp hours and a better inverter along with more solar so I'm going to pick up an induction cook top to try out as well.
Some more real world experience: This year we did not fire up the generator on our F-650 once, zero hours. Last couple of trips we made coffee on the stove instead of the coffee maker. Temperatures dropped down to -9C, or 15F at night and the furnace ran a lot, and it's not a real energy efficient furnace but it does produce some good heat, and the shorter days up here give us less charging time especially with a flat mounted panel, but it still kept the battery bank up reasonably enough to go for 4 days on its own. Equipment is:
2-Group 31 AGM batteries
Samlex 150 Watt solar panel with 30 Amp charge controller
Xantrex 3000 Watt inverter
So nothing real fancy.