If you are "not" asking a contractor to take the responsibility for system performance or warranty issues you should be able to get a contractor (or skilled labor) just to install the system per your instructions (and your design) . There are issues that you should review prior to starting, such as soil type for heat dissipation, well number and depth, piping material, piping layout (reverse return, etc) leak test of piping, physical installation of pipe (since the piping can come on a roll with no joints other than the U bend at the bottom of the well), grouting of the holes and grouting material (very important after the piping test is performed (and passed)), filling and air purge of the piping, is the circulating pump included in the purchase of the heat pump (?) big enough to overcome the friction loss due to elbows, fittings, valves and heat exchanger pressure drops, who is going to wire it (power and control).
If the system does not perform you cannot expect the contractor to take the responsibility of the system installation that was initiated per your design and/or directions.
Most of their profit is from the purchase and resale of equipment the rest is typically labor with a little MU. (They have to eat also.)
If you are sure that you can provide all the answers for your design, I would hire skilled labor to install the piping and HVAC unit per your instructions and hire a contractor to wire the unit and start it up.