What hose is needed to convert to 100 lb Propane tank

get 2 100 lb tanks and that just might last you 5 months.
change out both hoses to longer ones, keep your short hoses handy for to switch back when your done.

another option is go to a well stocked gas supplier (or welding supplier) they have all kinds of neat fittings (in some cases) you can have an adapter made to fit your existing tank hoses to extend them to go to the 100lb, and just take them off to switch back,,, put away for the next time you need them.