Freezing a large pork joint

I've been given half a pig
I'm cutting it up today and want to leave the shoulder and leg whole for roasting when we have a big family gathering but all my freezer bags are much to small.
 I've got a few plastic carrier bags , recycling bags, bin bags , tin foil and cling film, do you think a combination of them would do.
I'd be glad of any other suggestions

Thanks

Try some of the large strong garden refuse sacks. Not free but that's why but butchering the pig youself makes it cheaper than getting the butcher to do it.

Our friend, who supplies us with other meats, often uses the shopping bag method, and has been known to put a large frozen lump of meat though his bandsaw in the garage if he needs to make it smaller.... ;

I might try that.   

We wrapped them in  lots of plastic shopping bags and then 2 bin liners.
We left the leg and shoulder whole so they are big joints but that is what i wanted.  I'm going to roast the shoulder at Easter when the family are here.  I've done them before over 24hours in a very slow oven but this one is massive, I recon it must weigh at least 30lbs so  I'm trying to work out the timings.  The others have been between 18 and 22lbs taking 20 to 24 hours. 
Anyone have  an opinion, I think about 32hours.

I'm just staggered you have an oven big enough 

Got a big Britannia range cooker.  Main oven is 32inches wide so will take  big  joints easy.  Can also cook 6 big fruit cakes in  one go, great for using up eggs