Expanded polystyrene foam ("bead board") is friable and structurally quite weak. It dents and compresses fairly easily. Squeeze the old foam you removed with your thumb and compare it with the new foam. Moot point now... good luck!
From the grain in the blocks I think what you're using is expanded polystyrene foam (EPS - "bead board"). EPS readily absorbs water. What you want as structural flotation is extruded polystyrene foam (XPS).
I agree with L&VW. From the pics you posted this is not terminal damage. Over the years we've repaired whitewater 'glass canoes & kayaks broken in half, lengthened a 'glass guideboat by inserting a 2' section, done tons of fiberglass puncture & tear repairs, etc etc. If it's made of fiberglass...
Obviously re-axled. I'd like the axle to be moved more symmetrically under the trailer (plus add fenders as Beldar notes). I would check axle alignment ( to be sure the trailer tracks straight). I'd also double check axle mountings to the frame, plus (of course) check the bearings for noise and...
Boy, I think I'd just stick with your current expando plug in the DePersia. The Elvstrom needs a fair-sized hole in a pretty flat part of the hull that's also out of the way, but still convenient to reach--bit of a PITA all the way around in the small Sunfish cockpit. If used a lot the gaskets...
Elvstrom-style bailers work pretty well (better, I think, then the plastic Sunfish bailers), but can be a pain to step on with bare feet. If the boat is slid over beach/grass/dock/trailer bunk/whatever they're prone to damage if not securely closed.
"Old Style" plastic bailer - pre 1973
Part# 91025 (complete) - thread cap is 1-5/16" deep
"New Style" plastic bailer - post 1973
Part# 91026 (complete) - thread cap is 1-3/16" deep
Replacement bailer balls
Part# 91031 (for 5 pack) - balls are 5/8" diameter
To expand on what beldar boathead suggests:
Remember that when aluminum is crimped like this the aluminum work-hardens in the area of the crimp, and that area becomes more brittle than the rest of the spar. I would not try to remove the crimp or straighten this spar (= more bending & more...
Tri-grip pop rivets don't need backing washers, & have quite good tensile strength. See typical shear/tensile specs here:
There is lots of choice in head profile, shank diameter, & grip range (length). Many NASCAR...
Fill the old hole with your choice of polyester/epoxy goop, then redrill and fasten with tri-grip pop rivets. These rivets resist pullout well & install with a regular pop rivet tool: