If you don't mind my asking, Jrd, why do you want a brown/tan suit? Do you plan to wear the jacket and pants separately? How often do you think you'd wear it as a suit or as separates?
I could be way off base here, but I'm guessing you're approaching this as a way to check off two boxes as once: Don't have a brown suit. Don't have a fresco suit. Would like both. Why not get a brown fresco suit?
I make this guess because I've made decisions like that. As you may recall, I have a dk brown fresco blazersuit (3 patch swelled edges). I wanted a dark brown sport coat, and I got the pants thinking I might wear it as a suit. But if I could make that decision again, I'd just get it as a sport coat, which I wear often. Another regret is a light gray crispaire suit I bought. I wanted light gray pants, and I figured I might as well get the suit since I could use another lightweight sportcoat. (I did this despite the usual warnings against light gray sport coats.)
Neither of these was exactly about checking two boxes. But both were compromises motivated by impatience and/or the false economy of saving 10% for a suit vs. sport coat and pants as separates. While I do wear both as suits, I rarely wear either, since I rarely wear suits in general. But also because when I do wear a suit, it's usually more appropriate to wear mid to dark gray or navy.
So in the end, I agree w/ Foo. Only get a tan/brown fresco suit only if you have a bunch of blues and grays (as Vox does) and, I would add, only if you wear suits often, in many environments. Reagan wore that suit about 40 yrs ago, when suits were worn by more men in a larger variety of occasions and environments. Nowadays, men virtually never wear suits when and where a tan or brown suit would be ideal.
If you wanted to check off two boxes, you might get mid-gray fresco suit with some nice heathering. That'll look like sharkskin, even though it won't have the usual weave. You could of course, wear a tan suit purely for fun on the weekend, as Holdfast mentioned. But I wouldn't and I doubt you would either, since you mentioned your concern about how most people would react. Maybe people would find it normal in England, but I can't imagine a time/place in the US where a tan suit would be thought of as normal. Actually, I can imagine one, perhaps: a summer wedding. But in that case a tan cotton, linen, or cotton-linen blend would be better. And a washable version (Haspel, Luxire, for example) would alleviate your concern about cleanliness.
(Of course, being considered normal isn't the only value in life.)