Yeah, tails can be weird. The strip 21st Century Fox had the characters in spacesuits at least once, and the tail portion was as bulky as a normal uncovered tail.
In 'reality', a tailed astronaut would almost certainly have some sort of "wrap", like an ACE bandage, to hold the fur down, and make it easier to slide into the suit's sleeve without "rubbing the fur the wrong way". So realistically, Roger's suit should look like an armored rat's tail.
But you're right, you need to keep the profile- and hey, appearances sometimes override reality, right?
So try this: A tail cover that's the same rough profile as his normal appendage (or maybe a little thinner as at least a nod toward reality) with armor segments or "kevlar" patches that emulate the rings/stripes.