Oakleaf - It's possibly a difference in torso length, but the tsuami 145 is made for larger paddlers, while the tsunami 135 that NoNo bought isn't. Maybe try a narrower boat- it does sound like yours is big on you. I don't go beyond a 21.5 inch wide boat partly for that reason. The tsunami 135 is 23" inches wide, while the tsunami 145 is 24.5" wide.

But you can get some minicell padding and pad out your boat to make it a bit more comfortable - some padding under your knees to hold your legs into position will help with the thigh braces being in the wrong place. You basically just rubber cement the stuff into the kayak. You can either get padding and cut it/shape it to fit, or they sell knee padding.

How long is your paddle? In that wide of a boat & your size, you pretty much need to do a relaxed low angle technique and need a longer paddle to do it. Playing with your paddle & technique might stop you from banging your fingers. Do you keep anything on your deck? I basically keep a minimum of stuff on my front deck for that reason, I have a high angle technique that brings my hands really close to the front of the deck and I hit anything that I keep up there. If I really want to take pictures, I put my pelican case with my dslr up there but realize that I'm gonna be swearing at it every few minutes when I hit it.

As for bringing your elbows up high - Do not bring your elbows or your wrists above the height of your shoulders. That's a good recipe for dislocating your shoulder. So do keep your wrists & elbows underneath shoulder height (you probably already know that, but a lot of people dislocate their shoulders paddling if the boat pitches against them or whatever when they're in a bad position)

Does the tsunami have the same barcalounger type seat as the tempest does? Where there are straps that you can pull on in the front to bring the front of the seat upwards? You can do that to help support your thighs - the other nice thing to do there is to go ahead and stash a hydration bladder under the front part of the seat, it pitches your legs upwards and supports them. I do that when I'm going on multiday paddling trips and need to put several bladders of water in my boat. But padding underneath to pitch the front of the seat upwards would help.

A PFD might be too thick, but if you get 1-1.5 inch minicell padding or something like that, you could put a thin layer on the seat to boost you upwards - just remember if you lift your seat, you are lifting your center of gravity somewhat higher and it does affect how the boat feels.

Minicell doesn't absorb water and I'm sure there's some other reason everyone uses it for padding out kayaks.