how would this be fit into a suit?

[afewgoodmen]

I guess it would have to be tied down onto one side or another.

[Cambridge Paul]

Queen Victoria's solution — a ring through the end to hold it up!

[Byron]

That is urban legend suggesting it was my darling husband's preferred method against the unseemly prominence of male genitalia in tight trousers although I was not aware of any such appendage prior to bearing nine children.

V.R.

PS: King Henry VIII had a more comfortable piscatorial option but dress style inevitably changes through the centuries and I can only reply to your question by saying "with great difficulty"