My club imaginations campaign allows anyone in a tricorn to take part - so we have the Duke of Campari - an rather fusty and elderly gentleman with some unusual tastes who has not spent a penny on changing his armies uniforms since the early 1700's. Wargames Factory WSS figures make up his army as they do the regiments of Sir Arthur Guinesses Irish mercenaries. My own army is based on Perry Hessians but in white uniform, befitting the army of the Archbishop of Hoegaarden. Now there is quite a difference between the tight style uniform of the AWI and the loose almost simple uniforms of Marlborough's day, but perhaps not as much as between those of the following century. However the Austrians sometimes make an appearance in the campaign and when they do its in their late, post SYW to revolutionary period Casquet headgear.
That's as wide a range as I'm prepare to include, but it's your stuff, go wherever your whim takes you.