Hi Tony, I'm in the NE of Scotland, went down the mini bale and wrap for haylage route , not so weather dependent and able to store it outside.
As you have realised the set up cost will take along time to recoup in finance terms. As for selling surplus you are going to have to compete with the big boys , one makes in big bales then rebales and wraps later for sale, another makes his haylage in the mini size ready to go and another rebales in to vacpacs . All 3 are very efficient and rely on the economy of scale.
If you produce for some one else be sure they know the cost before starting (Fuel , wear and tear ,your time ,net and bale wrap ) and remember you arnt a charity, there is a market but it depends on how much profit you are looking for to undercut others
I wont cut and bale for any one else ( or lend out kit )for the following reasons , I have damaged equipment in other folks parks , the surprise set of harrows in the long grass or "sure there's no stones" just chuffing big rocks that the mower wont cut ! and finally HOW MUCH !!!!!
On the upside the saving on waste and ease of handling will help offset the production cost.