Are you going to tell the A.I.'s how to conduct wars under two different rulesets? The game has to be built around the decision on this point, around both AI and the combat mechanics' tie-in to everything else.
If a game is 1UPT, it should have longer movements per unit and include a join feature that lets units of the same class combine their hitpoints, to address traffic jam problems. To leave the stats as they have been in the past, and being turn based, means that each individual unit is the defender of its position, right? But the division of the unit classes, by technology, makes many of them extremely unsuitable to doing that. This is fine, in a tactical game where fronts move and the defended position is more of a broad area. This is a HUGE clash, however, with the other end of the Civilization game, where these tiles that are being fought over are all, individually, quite significant; representing a complete neighbourhood, a complete resource-extraction operation, or the city center itself. The scaling problem isn't just a finicky thing of not liking wars fought over a thousand miles, it's a risk/reward clash of two dynamics that want two very different things for the game.
But, I suppose if the game is jank in one of these rulesets, that doesn't mean it can't be there. So long as it is made and properly balanced in one of them.
I prefer 10 units per tile, I'm quirky like that. Or, it is still possible if the game exits the dichotomy, and retries the unit editor, where we compose a unit with various perks from among the technologies we have researched. Mounted elements, artillery, spears, swords, bows. These things enhance an *army* and the army (with its implied local commander) figures out its combat effectiveness beneath the notice of we, the grand strategy helm. If you want to keep the tactical gameplay from the series up to this point, which you do if you're still attached to individually positioning archers, spears, tanks, and artillery, then you have to accept how tactical that makes the entire game, and accept design decisions that build on that fundamental pacing, risk/reward, and the rest, from the start.