I wash my 4x2 Fleece Bedding in a large Wash Bag in the machine and it comes out lovely and clean
With a piece as big as 7ft, it might be worth cutting it into 2 bits as aside from actually fitting it in the machine you also need to make sure there is plenty of room for it to move around freely to aid agitation and therefore cleaning.
Before I wash my bedding, I give it a good shake, hoover it and then don a pair of Rubber Gloves to give it a good wipe down (circular movements work best), it's amazing the amount of hair and stubborn bits of hay that can be removed by a good old pair of trusty Rubber Gloves!
If you find it still isn't clean enough stick it back in the machine and give it a rinse with some white vinegar, this can help remove any stubborn pongs and can also soften the fleece without interfering with it's wicking qualities. Avoid using Fabric Conditioner!
If it helps I happen to think I have the worlds smallest Washing Machine!

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