It never struck me as wise to drop anchor off the same end of the boat the prop is on, so I go to the front.
Your logs have a solid portion all the way at the front where there is a hole drilled through. The gets used as a tie down by most folks, although I think it was a lifting point at the factory during assembly.
Anyway, go take a look at the front of your logs and you'll see what I mean.
Then go down to your local hardware store and buy yourself 2 or 3 Stainless Steel quick-links. They look a lot like those carribiners that mountain climber mountain climbers use. You want the kind that opens and closes with a screw mechanism, and I'll leave you to judge size for yourself.
You put these on the front of your logs, screw the closure down and you now have a handy place to run your anchor line through. Just remember to put a wee bit of anti-seize on the threads so you can open it up again if you want to.
I have seen people use this sort of setup to drop two anchors, once off each outboard log, and another guy who anchors off his center log and uses an additional couple of "clip" style 'biners to hang his rode off the two outboard logs.
I should add....
Most places where people use pontoons are not deep enough for a chain rode to really matter. That's a length of chain; one end of which attaches to your anchor clevis and the other to your anchor line.
Personally, I use one anyway on the theory that it can't hurt.
Regardless, you're the one familiar with your lake and what you want to do in terms of anchor/line/etc.
I just wanted to mention that if you plan on pulling your rode THROUGH the 'biner, make sure that what you get is size appropriate.
Me...
I just pull up the anchor until the end of the rode is at the 'biner, then brag the chain and lift the anchor onto the fore-deck. AFTER splashing off the mud of course...