What is an alternative to a cement truck that would allow more working time?
The time from when the cement, water, sand and particulate are mixed till the time the mix should be in your forms is limited. That is a primary reason that a delivery truck can only stay at your lot for a max time (they have a secondary consideration of keeping the truck on the road delivering other jobs but many companies may stay longer for an overtime charge).

Since you need a lot more time and 10 yards is an awful large amount of material for one person to handle all at once you are left with two choices.
1. Order raw materials and rent a mixer and perform small batch mixes on site.
2. Prepare all your forms and rebar ahead of time and then prepare to have a crew available to get the job laid down in the time that a truck can be there.

Note that if you are doing something in small batch mixing this is not the best approach when there is slab work and continuous foundation that you would like to all bond together. There is also the issue of getting a slab surface finished right when it is poured over too long of time in small pieces.