One if my club mates makes maple sap beer. I believe he makes a pilsner due to the very light flavor if the sap. It can be easily overlooked if you don't know it's there. There was some discussion about the sap water mineral profile also lending to lighter beers. The problem with adding extract , in my opinion, is that the water used in the malting process contains all the original minerals. If you truly are interested in the flavor coming through wholly, without influence from extract, maybe try going to all grain with a friend who can help guide you, or try Brew In A Bag.
I brew almost exclusively BIAB, and it's easy to make the jump from extract to AG with only a couple dollar investment. Get a nylon paint strainer at the hardware (my stire sells 2 five gallon strainers for $4).
Using your existing kettle and equipment, add your grains to the bag, steep in the sap/water for an hour, pull the bag, and continue as you have brewed. Not too difficult, and can help you decide if you want to move up to AG, larger batches, etc, or not. Ymmv.