For a Flashman-type sf/fantasy protagonist, you might want to try Hugo Award-winner
Mike Resnick's
The Chronicles of Lucifer Jones, for which the 1st book is currently being offered
free for the month by the publisher and the next few on promo tie-in sale.
It's one of those outrageous tale-telling wacky globe-trotting adventure pseudo-historicals centred around a shamelessly selfish con-man posing as a preacher who sometimes, but not always, gets the better of the people he openly attempts to lie, cheat, and steal from. I'm only a few chapters in (can be read like interlinked short stories), but basically it's a lot of unrepentant reprobates going up against other unrepentant reprobates and may the best con-man win.
These are mostly pretty funny so far and according to the blurbs, there'll be fantasy elements introduced later on, but I'll warn for Kipling-esque gung-ho paternalistic colonialism attitudes in the 1st person narrative (current portion of the volume I'm on is set in Africa, and there's use of retro-30s white stereotypes about the natives, mostly for comedic effect which some people may feel too close to to want to read in their entertainment fiction nevertheless).