I guess this is way too late, but just so you don't think you are being entirely ignored… .
Yes, that is pretty good. Since you asked, though… .
“As it stands… makes it difficult…” is incorrect, as there is nothing doing the “making”. I would say, “…clients, it is difficult…”.
Kudos :) for using “within” instead of “in”.
“Manner” is about, for instance, how one person acts when helping a little old lady across the street (versus how another person does the same thing), or how a professional comedian tells a story (versus how a typical person would) — tone of voice, how you hold or move your arms, and the like. Here, I would just say, “…the way in which…”. (It does not sound impressive, but it is not all about using big words. (Actually, for many people, it is!) )
“Set”, is good. “Scheduled”, would be fine, but (splitting hairs here) “set” emphasises the fact that they are fixed, where “scheduled” suggests slightly that they could be some other way. (Again, most people would go for the bigger word.)
I would prefer “reimbursement” over “coverage”; the latter is about protection, a little bit. (Conversely, the latter might be the meaning you want.)
Strictly in terms of English grammar, it is phrased fairly well. If you (and Stack Exchange) will pardon me, I would suggest that this is a sentence slightly too complicated for easy digestion. It might be better to say something like the following.
[If you were just conveying the meaning, you would just say, “I should receive reimbursement…”. Here, however, you want to soften it, to be more polite. There would be many ways to put that, but I am not be best person to ask about that.]
“Ideally, I would receive reimbursement for all my travel time and mileage. As it stands, given the way in which my work hours are set, it is difficult to see other cases within the time window set for me to see clients, and still be fully reimbursed.”
(Most English speakers would just say, “…stands, the way my hours…”, I’ll warrant, even in a business environment, but it is more correct with “in which”.)
I hope it went (or will go) well!