The biggest difference will you find between the 1/2t and 3/4t are the axles and brakes. The semi floating axles of most 1/2t vehicles have about 4000 lbs of rating from the truck manufacturer while the 3/4t full floating are rated over 6000 lbs. This affects your vehicle payload capacity the most. With just two adults and a bumper pull, you will probably not have capacity issues with a 1/2t. Add a couple kids or big dogs to this along with some toys or firewood in the bed or cargo area and you may find you do not have sufficient payload for your tongue weight.
Until you weigh your current setup when it is packed up, you will not know whether you are safe, borderline or over your current vehicle ratings. The fact that you are thinking about this may indicate you are at that threshold, but only you have to ability to find out.