I routinely get by with 30amp service even though I have to reduce my 50amp cord with a 30amp adapter. I use my water heater almost all the time and on those cool nights, I'll use my 1500watt space heater on low which only draws 800watts. If we need to use the microwave, we turn off the water heater for awhile - same of a hair dryer. You can easily get by on 30 amps as long as you remember you can't operate more than two large draw appliances at a time. The water heater and the air conditioner - the air conditioner and the microwave - on a cold night, we'll run two heaters on their low 800watt settings and leave the water heater on. If it's really cold, I turn off the water heater and turn one of the heaters on high and that usually keeps us warm and toasty.
I also use dielectric grease on my plugs to prevent the corrosion that causes increased resistance and heat which turns the plugs black and ruins the sockets. I haven't had any problems with my cords since I started using the dielectric grease - highly recommended!