you sound like you are either an engineer or a computer software sort of guy [...]
I feel its unrealistic to look for some sort of "calculator" that can give you a black and white number
My training was indeed in applied mathematics (econometrics and market models). So yes, I tend to use numbers. I've updated the OP after finding almost exactly what I was looking for.
---
You suggest that I ride hills similar to what I expect to encounter, but see, this is the problem -- I don't know what to expect. Here is what the ACA has to say about the Sierra Cascades route:
The Sierra Cascades route lets you warm up slightly before the first major climb to Rainy Pass at 4,855 feet. Once you cross to the eastern side of the Cascades the route will be rolling and following river valleys until Blewett Pass. West of Yakima, Washington, is where the climbing begins to approach Mt. Rainier National Park. The route begins climbing and descending passes until the Columbia River Gorge where it's mostly level riding, then there will be more climbs and descents south of Mt. Hood all the way to Crater Lake National Park. On section 3 and at the beginning of section 4 the route stays on the eastern side of the Cascade Range but still expect rolling terrain. You'll climb into the Sierra Nevada south of Lake Tahoe (more passes), then stay at slightly higher elevations along U.S. 395. Tioga Pass, at 9,945 feet, is the eastern entrance to Yosemite National Park, and is the highest pass along the route. As you continue southward, the route continues to go up and down and becomes more rolling as you reach the border.
"Rolling". Contrast this with one of the first comments posted on the Sierra Cascades thread I started.
The SC is exceedingly difficult so expect even shortish days to be hard compared to most other routes. Services can be pretty far apart, so it may be hard to do short days in many places. Not saying you can't do it, but I know that I was pretty much at my limit even packing very light. No way I could manage that route with young kids in tow. You may be fitter and tougher than I am/was.
My "analysis" agrees with @
staehp's comment.
---
My drivetrain is 48-36-26 x 11-34 and there isn't much I can do to change the ratio. And as far as the load goes, I will have to carry gear and supplies for the whole family (we are ultralighters, so that means roughly 20kg). My wife will ride with our little one (so I can nag them, or vice versa
---
Again, if it were just me, or my wife and I, I wouldn't have bothered. But pushing bikes uphill with a 5yo is not a fun way to spend a Summer (our little one will ride here own bike, hooked to a follow-me when she's had her fill -- pushing bikes would be a major annoyance).
So it now looks like EV6 is back.