Subsoiler or trencher for utilities install?

[topbuilder]

"end up costing more than I'd save" Agreed. You need the best machine you can get. Not one someone is getting rid of. A weekend is optimistic for a first effort. Correct, rent the machine on what ever is their last day of the week. There is usually a charge for going over 8 hours but not as much as 2 days rental. You can roll out a #12 tracer wire on top of everything at 6-8" to mark the trench. Just remember any repairs will be done from the side of the original trench. Water line should be minimum sch 40 at that depth. If you use PVC, use bell-end couplers, the long ones. 20' pipe, not box store 10'ers with the short bell end couplers. Upsize your conduit. Not much difference in cost between 1 1/4" and 1 1/2" for example. I don't know what size electrical conduit you need to run, but that long of a run, extra room means the difference between easy pull and can't hardly do it. I usually cheat and slide the pipe over the wire and throw it in the trench complete. As a builder I plan the mechanicals so I do not have to pay the subs for separate trenches. I do it myself. One trench. None stepping on other subs work.
You know how as men, we tend to misunderestimate the amount of time and effort a project requires? You are embarking on such a project...

 

[topbuilder]

Not to get in your business, I hope you are not running 840' of primary electric? Too far. You would have to have a transformer set. It will cut down your distance, but your "contribution" may be a little painful.

 

[Sun Treader]

The run from the transformer to the main distribution point is about 100' and the longest run from there is about 300'. The longest possible run from distribution could be further but it wouldn't be high amps.

 

[RNeumann]

This continues to get better

 

[plowhog]

I bought a used ditch witch walk behind trencher for $2,400. It digs pretty fast and results in a much cleaner trench than a backhoe can do. It seems multiple utilities in the same trench is something to consider. Yes, you can do it as code in most places allows that. But, it usually requires 12" horizontal (and vertical) separation. That means at least a 16" wide ditch. I can dig two ditches, 6 inches wide, much faster using my trencher than a single ditch, 16" wide, using my backhoe. Something to consider.