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Typically one or more of those items will force a Class B user to connect to some form of grid support after a few days out. ....
The AVERAGE user, yes. But not the customized off-grid user. Here's a point-by-point response to those factors in our case:
(1) Waste tank capacity – Currently about 10 days on general principle when off grid and remote (it could be made to stretch longer, but would I want that?). If necessary, this factor could be made to be pretty much unlimited (dig a latrine with a proper composting structure - I know how to do that given my personal history).
(2) Fresh water capacity – Unlimited in my target areas (fresh water sources)
(3) Fuel capacity – Not a limiting factor as boondocking to me means not moving much, or just moving a few miles locally from one trailhead to the next.
(4) Laundry handling – Not a limiting factor – when required, I do it the way it was for almost all of the last 170,000 years of human evolution – by hand. Our clothing is selected to be readily hand washable (quick drying fabrics).
(5) Garbage handling – Not a limiting factor, as it is burned.
(6) Recycling handling - Not a limiting factor, as it is burned.
(7) Food storage capacity – With careful planning and preparation, we have the potential for at least 4 weeks if we wanted to stretch it that long, in part because we
custom-designed a Yeti hitch carrier in which we can use either water ice or dry ice. Our fridge is a Danfoss model, so its capacity to keep cold (including the freezer) is also unlimited due to the battery system described below. If we wanted to remain out a REALLY long time, we could stock dry and canned goods with very long lifespans.
(Eight*) Battery capacity – Unlimited in our case (300 AH lithium with 300 W solar plus an upgraded alternator that can use in a pinch to recharge the battery without draining too much diesel). (*I don't know how to turn off the sunglasses emoticon which auto-fills when the number eight is put in brackets)
Edit: (9) You didn't mention propane. While it's nice to have, I can get around that limitation by (a) having very good goose down sleeping supplies (blankets and bags) so that I don't need to run the van's furnace, and (b) using biomass for cooking and heating water for washing purposes, and to make it potable. Pic below of my Kelly Kettle, which is a highly efficient water boiler. And my biomass supplies truly are unlimited for this purpose.
We haven't pushed our van to see what kind of a record we could set with it for unsupported off-grid use. Neither one of us is retired, so we simply don't have the time for that right now. Maybe some day.