Don't know where to buy spare bags but if you or anyone you know is good with a sewing machine, you could cut up a groundsheet to make your own and use and use some guy rope or other cord as the drawstring.
If that doesn't work, try your local tent stockist.
When our car was nicked last year, all the bags for the camping equipment were in the the top box.
Went into our local camping shop and they ordered a replacement for us. Just had to promise that when it came in the shop we'd def buy it as they wouldn't be able to sell it on.
A friend of mine had a similar problem when his new frame tent turned up with all the poles in one bag ................... it took 3 of us to lift it in and out of his car ... lol
He got round the problem by buying some of the weather protectors (canvas bags) for the carousel washing lines .......... sounds daft I know .... but no more hernias!!
Cheers, Moooosssseeee
------------- Give me the Grace to accept things I cannot change and the Courage to change things I cannot accept.
I found the perfect solution for my outwell Vermont poles. Army canvas kit bag purchased from eBay for £5.50. Heavy duty canvas with brass eyelets to fasten. available new and unissued from Army Surplus stores for about £10.00
Thanks for that link Geetee, just sent off for a quote. We've being thinking we need a waterproof bag for the mattress in the TT as whenever we've packed up in the rain, the mattress always get wet, with the awning packed up on top of it. Which is Ok, if we're coming straight home and can dry it out, but our next trip is to a few sites and don't fancy sleeping on a wet bed. LOL
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June - Sandringham Est, King's Lynn
July - Clumber Park, Worksop
Amazing family weekend with old steam engines, classic car displays, market stalls, and full catering and bar. And camping on site - Save £25 by booking in advance.