We do most of our sailing in the ocean splitting our time between the Tampa bay area and Key West (Florida Keys) which is a probably different situation from yours. Our typical trips are 20-40 mile day trips (seldom overnight). We use our TI for mostly scuba diving/snorkling, spear fishing, and island hopping. Figuring your boat to average around 5mph, a good day for you would be 3 hrs to somewhere (15 miles), and 3-4 hrs back to the same launch point.
Since we travel in open water alot I installed an emergency gas motor on my TI (my just in case motor) and always 50 miles worth of fuel (1 gallon). The motor was seldom used, anytime I needed it we were usually in dire straights. On one trip we were 15 miles west of Key West and ran aground on a shoal and broke the rudder, making it impossible to sail upwind against a 15 mph headwind. We used the motor to get back to Key West. Both my wife and I can peddle the TI for 8-10 hours on one day, then get up and do it again the next day, so lets say your wind dies and your still 5 miles from launch, it's not a major problem to peddle home (unless you are fighting a strong current (up river, tides, etc), of course you will need to build up you legs for the task, don't try it on your first outing. If your legs get tired, you can always paddle also. Around here often the winds are very light (5-7 mph) so we typically leave the sail up, and also peddle to maintain a decent speed (almost always faster with the sail up verses sail down). Actually the TI is one of the few boats out there that can generate it's own wind By peddling while sailing in very light winds somehow the sail works as a wind amplifier, where when everyone else is in irons, we pass them all up pedaling lightly with the sail pulled tight and waving as we pass by them.
In the winter in Key West the water gets down to about 70f, I always have a wet suit on board just in case something happens. I can get my shorty wet suit on in the water, and if I get colder I also put on a bib wetsuit that covers my core and legs with a double layer (2 x 3mm = 6 mm wetsuit). The bad thing about a dry suit is if it's warm and you have the suit open to stay cool, then go over, the dry suit becomes a weight as it fills with water (pretty useless). So for the dry suit to work it must be sealed at all times (pretty tough when it's 80 degrees and sunny). Plus it makes a difference how far from shore you plan to go, if you only go a few hundred feet from shore, most of us can swim to shore without a wetsuit. But then again it's all what your body is used to, I grew up in Canada, in the summertime the water only ever gets to 70f, it never stopped us from swimming, sailing, and diving most of the day. But it all depends on what you are used to, and there is always less risk with groups of boats.
Hope this helps