A couple rolls of pennies or a railroad spike will stop the plane from floating, and doesn't cost too much either

Actually,
--Tack streamers on to up the drag, not like a trainer needs to go 75mph anyway
--Shim / washer the rear of the wing 1-2mm to get a more neg inc to gain drag & offset the abundance of lift. I had to do this to a 6' glider I put a pair of Norvel074 on, so much speed was a pain to stop from climbing without shimming the wing, all landings had to deadstick
--Flywheel a small prop with a big spinner, or even a fenderwasher or 2 on the propnut for flywheel, made my 4stroke sound like a Harley.... ok, not just like a harley, but I used personal bias listening to think of it that way.
--Put actual flaps on: split flaps & a $9 servo