It is very difficult construction, I think better will be to hire mini crane with specialist.
I also don't think you should build a crane by yourself. This may not be safe. I'd recommend you to use the small crane hire service. Operators will find out all the necessary details from you, assess the risks, and tell you about the working conditions to carry out the work at the highest level. I guess that this is the best service I've worked with within this industry.
get a counturweight cran the short end has lots of weight
and the long end picks things up ad the counter balamckeeps it from falling