Read every post and I don't think anyone has asked how or what your company is doing or how it is run NOW. Do you have a wad of cash to fall back on if it goes horribly wrong? Have you asked the contractor if they would be willing to regionalise the contract? They would only be dealing with 5-7 contractors if done properly. National from a one man band overnight has to be too big an ask. But if you have a few vans and lads already, maybe it is manageable. Not many people become successful from one big hit in any field of work. But they do from having a few smaller hits of worth.
Bottom line is.....the bottom line. If the profit does not outweigh the grief, don't do it.