It depends on the situation. 40 weeks absence in 5 years is not a big deal especially if all of these are 1 week trips. But a pattern of trips counting up to 2 years might be a problem, and if you can justify them with employer's help - why not. [ BTW, I am not saying the OP has 2 years worth of trips. That's just an example. ]
A simple format will do. To whom it may concern ... or to the CIS. This is to confirm, on OP's behalf, that he/she undertook the following travels due to company business.