Tony, yes my boat is heavier than the day I purchased it. However, as we have already discussed at length, it is the result of my modifications, not water intrusion. It was evident to me, after taking delivery on my boat, two things would eventually contribute to water intrusion issues with the TDB-14 hulls as built. The balsa core in the hull results in too much flex, particularly when you toss in the additional torque of running a 25 hp on the motor board. As with any through-bolted system on a boat, if you don't do routine diligent maintenance via resealing the bolt channels, water will intrude into the motor board-your photos illustrate this issue well. You can actually retrace the water intrusion path from them back to a bolt hole. The crack below the fire extinguisher on the starboard floatation chamber's base is the likely site of water intrusion into both the floatation foam chamber and the deck.
If you let water sit pooled in any fiberglass boat, migration will occur... As you state, reasonable maintenance and care will keep any older duckboat fully functional.
I would encourage you to seriously consider the motor mount design Alan Hoeweler submitted on the TDB website as a re-work for the TDB-14. Beyond the very nice addition of the step, it contains two braces that can be bolted to the stern decking for additional support and motor torque offset. A modern four stroke 20 hp will be adequate power for this hull, even fully loaded. Keep in mind that somewhere back in the '90s prop rated horsepower became the reporting norm for outboard manufacturers-modern small blocks put out adequate power, with significantly improved power to weight ratios over the early 4-strokes, particularly with a four blade high-thrust prop to augment hole shot.
I stripped the interior paint off my boat upon delivery in 1995, reglassed the interior up to the under-shelf foam chambers and five inches above the junction with the rear foam chambers with three additional layers. I added a battery stand on the port side up front, immediately behind the bow storage locker, wired (Ancor marine awg) the boat for: navigation lights, a lighted interior Ritchie compass on an aluminum swing-out bracket on the cockpit gunnel, a hand-held light flood light, and five low amp draw interior lights as well as a fuse block and the two circuit switches. I have a flasher unit mounted on the port side floatation chamber bulkhead with the tranducer siliconed in place to shoot through the hull where there is no balsa core material to aid in gauging how shallow I am running. I will be mounting a six amp dedicated battery charger this year. I added floatation foam to the outer 2/3s of the bow storage locker, after building and mounting two bulkheads in the storage chamber (actually, I cut two panels out of the fore-deck storage shelf for mount access and then reglassed two layers over the existing decking after I shaved the floatation foam back to level when the pour set-up).
My deck is sealed with three coats of Tuff-Coat rubberized paint that extend up onto the interior cockpit walls as well as always being covered when not in use by the hard cover. I also sealed the seam junction between the hull and deck pieces with 3M 5200 the year I bought my boat and inspect it routinely.
For anyone who stores the TDB-14 outside in freeze/thaw conditions, I would also recommend that they put a tarp over the boat to keep water from working into the junction of the stern section and the motor board from above, as well as provide UV protection to minimize chalking of the gel coat.