I wouldn't worry too much about the tramp capacity limit, I weight more than 200 lbs and have never had a problem with the tramps unless you stand on one of the clips, in the 4 yrs I've had islands with tramps always on, I have only broken one clip, as a result of standing right on the clip with all my weight, (they are easily replaced, and under warranty for two yrs). (PS the newest TI tramps have much stronger clips, if you buy new tramps they will likely have the new stronger clips, (I'm going by what I saw at the dealer on a new TI on display last time I was there)), it would be worth asking about anyway.
We are scuba divers and often use our TI as a dive boat with as many as 4 passengers at times (one in each seat and one on each tramp), yes the boat is overloaded a little but seems to survive with no difficulty, we don't do anything crazy when out with 4 we just launch at Higg's beach in Key West then go out snorkeling or scuba diving just off shore only in light winds, and nice weather. We have an inflatable 4 passenger boat that we tow behind the TI usually with all the scuba gear, tanks, coolers for the lobsters and crab when in season), beer and food coolers, etc. We have also gone out pulling 3 or 4 other kayaks off shore (as many as 8 people) many times where we just anchor someplace just off shore and snorkel, and usually have a picnic out on the water (like a party barge). We have a motor on ours (Honda 2.3), plus lots of extra sail (265 sq ft), plus a nice ladder for climbing on board with scuba gear, and we have a really good anchor ( a guardian G7) which is very important when diving since you don't want the boat to blow away. We beach launch all the time, actually the TI is so versatile that there really is no time you can't go out, in light winds of course you will likely need to pedal some, with only 90 sq ft of sail TI's are not as nice as a cat in lighter winds. Once the winds get over 10 mph, then the TI is in it's zone, since the sail is furlable your pretty safe up to around 20 mph winds as long as you furl the sail in a couple turns, or more in higher winds (they are really difficult to tip over (unlike any cat). You can pretty much count on the TI to sail between .6 and .75 of wind speed typically. If the wind dies you can just pedal expending very little effort, both my wife and I can pedal for 10 hrs (mostly exploring rivers and such), then get up and do it again the next day.
Think of your TI as a family fun boat like an SUV, there is really nothing you can't use it for, which includes just using the hull alone (no sails and AMA's) as a kayak, the TI turns out to be Hobies fastest and most versatile kayak when in kayak mode, though they don't sell it as a stand alone kayak (you can't buy a TI kayak only).
Actually don't get to comfortable sitting in that center seat, if you want to get more performance out of your TI it helps to hike out on the tramps using your body weight to help keeps the AMA's out of the water (just like you do on your cat to prevent tipping over). I have a tiller stick (a piece of 3/8 PVC pipe with a simple rope loop on one end) that I steer with when sitting on the tramps (hiking out) and hike out using my body weight so I can show a lot more sail and push the boat more.
Hope this helps you