Welcome "finalgang"! Hope we can help.
I did a very quick check and found that there are a number of COE parks on Canyon that have group areas that can be rented. Haven't been to this lake so can't say what the facilities look like. I will say that there is a VERY nice group area on Lake Whitney (McCown Park, COE). "Corps" park facilities tend to vary so it will be a good idea to visit the park your interested in prior to committing. Here's a site that should get you started. Let us know if there is any other way we can help.
Canyon Lake Offical Web Page
Hope you have a great wedding and,
Happy Camping!
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Turn Key, DW & Tilly, The Camping Boston Terrier
'03 Chevy 2500HD, 4X4, X-Cab, Long Bed
'04 K-Z "Durango", 275RK ("Sunday Haus II")
Twin Kayaks, "The Ride" by Wilderness Systems
North Central Texas, Where The West Begins!