[yorkie_chris]

Yes, will be fine. I've done the same with an old tent (huge) and army issue sleeping bag (hardly compact!). As well as having the essential 24 cans under it all.

for total security you could put a blanket over the tail, and use a ratchet strap around the lot. I have used this to good effect with bergen and panniers, stuffed full. It didn't shift an inch!