If I have to use a marker rod, I use a stiff rod loaded with Kinetic marker braid, which has zero stretch giving much better feel and sensitivity than any mono can. I only use a lead of around 3oz and never a full marker float set up. I find marker floats stick in any weed and therefore do not give as much feel as just a lead. A lead with also glide across the bottom far better, and with some of these spots being tiny, often just getting a drop without pulling back is all you’ll get. Also, a lead only can be teased out of any weed, where as a marker float with catch hold of weed and again, not give you an accurate reading.
It can be the case that once a clear area is found, you can then clip up and add a marker float for visibility. I prefer to clip up once I’m happy and have the area sighted up with a far bank point, and then wrap it up, and doing the same then with my actual rods and spod if needed. This also causes less disturbance in the long run, and once I have recorded these spots, I can just wrap up my rods next time and be straight on them.
Avoiding or minimising disturbance is another issue with weedy lakes, and i’ve often found myself repeatedly casting until i can find somewhere clear to present rigs on. As such this is almost unavoidable, especially as i won’t be happy unless i know for certain my rigs are presented in clear enough spots to be fishing effectively. It can be a case that you just have to do it, but if i can, i try to map out swims when i’m not actually fishing if possible.
This is a big advantage and takes a great deal of the pressure off when first getting set up, especially if you are late arriving etc. It can also help by not assisting others in showing them your spots, that you have worked so hard to find! I don’t want to be disclosing these to people who are watching, so being able to have your rods out with one quick cast can avoid giving away your hard work!