Travel Expenses Question

[yevdan]

I am Canadian and my consulting business is incorporated in Ontario. I am doing the vast majority of the work for a single US client, operating from my home office in Canada.
Client pays me on the hourly basis.
My client requested and I submitted W-8BEN form, so I am considered as a foreign company and supposedly will not have any involvement with IRS.
Occasionally I need to travel to US for some job related meetings with the client.
My client agreed to compensate my travel expenses on per-diem basis (lodging and meals) plus airfare, car rental and gas.
But at the same time my client expressed the concern in this regard.
He is saying that If I claim the travel expenses that means I am doing work in US and it can cause some problems to them while being audited by IRS.

Do I really need to stay 100% of a time in Canada in order to keep away from IRS ? And actually I am traveling as an employee of my corporation and client reimburse my company for this. Does it make any difference ?
I would really appreciate if somebody can help me with this issue.

Thank you