cyclopath256 , check Amazon in your country to see if some very affordable padded cycling shorts and bibs are available from Przewalski and Cerotipolar. I've worn both, some pairs going on three years now, and they're outstanding values.
There's nothing wrong with wearing snug fitting wicking fabric underwear with cycling shorts. Under Armour, Russell, Ironman and others make excellent quality boxer/briefs from the same Spandex and Lycra fabric used to make cycling shorts and padding. They have no seams in the pressure areas, don't bunch up, no problems at all. These aren't loose fitting boxers but form fitting compression shorts. On the road they'd be easier to clean and quicker to dry, and less bulky, than multiple pairs of padded cycling shorts.
But if you read interviews with some long distance cyclists (including Lachlan Morton, who finished his alt-Tour de France a few days before the official TdF, and rode more distance and elevation), they'll often mention skipping personal hygiene for days at a time and getting pretty stinky. Some folks can get by doing that and not suffer saddle sores. Some can't. Only way to find out is to try it.
But for the price of a package of 3-5 pair of those underwear, you can buy another pair of decent padded cycling shorts or bibs.