Hourly pay vs. pay by the project

We have 3 mobile homes in our park that we are currently rehabbing. I have 2 guys I am paying hourly right now for the work. They are not employees and they will be 1099. I have them take pictures before the work begins, during and then when they are done. They then send me their hours and I pay. They are competent workers as I was out there for 4 days and they worked hard and knew what they were doing. Now that I am not onsite the work that is getting done is taking about twice as long as it should be.

I was curious how other out of state owners pay handymen, either hourly or by the job. I am thinking of having them submit a bid on a certain project and then pay when the work is done and pictures have been submitted. This way they cant milk the job.