The Poldark series of 12 novels begin 1783 and end c1820. Current TV series is book 7 and approximately half-way in chronological time. This series is c1797-1799.
Accompanying articles in Radio Times and on websites have items on clothes. There's a variety of fashions in dress, hairstyle, headgear and footwear in the TV adaptation, depending on age, rank, occupation and character of a person. Older men wear wigs, younger men don't. The main male characters have shorter hair than in the 1970s TV series.
There's quite a lot of farming in the first book. Ross's father was the younger son and inherited only a small part of an estate. Ross in turn inherited a run-down farm, a derelict mine and a few cottages. He spent the first year trying to make the farm function. He was a hands-on farmer in the early days.
It's clear in the books that he wore outfits appropriate to whatever he was doing. A set of clothes was kept for the mine. There would be old clothes for farmwork (maybe he wore a smock but it doesn't fit his image!) Probably 2nd-best clothes for riding into town on business or visits to neighbours, business associates, friends and relatives. He didn't attend church so didn't have a "Sunday-best". Important social occasions required meticulous attention to his appearance. Costume of the character on TV doesn't show any of that. He seems to have worn the same basic outfit for everything for 15 years, with a new waistcoat occasionally and a fresh cravat at formal events. He wears boots everywhere, even in the bedroom!
A neighbour and distant relative of one of my yeoman farmers was a prosperous farmer at the same time as your man so I'll be interested to see or hear your impression of him. This gentleman was co- founder of the district agricultural society. His name was frequently in lists of prize-winners published in local newspapers, unfortunately before photographs. His father's estate was worth around £3,000 at his death in 1811. One of "my" neighbouring yeomen died a decade later with an estate worth "less than £1,000".