This is the million dollar question isn't it.
I believe that there are a few SWA's that you do not have to make reservations at, but from what I can gather, they get hit pretty hard.
Loveland has Simpson Ponds, Boedecker Res., Lonetree Res., and Big Thompson Ponds. Boedecker and Lonetree are big water and a boat would be beneficial.
You can also hunt on Boyd from shore, but it's $6 a day to get in.