Great idea I'll think some more and sift through the resources that I use frequently, but seeing as it is summer in my part of the world, here's a post on masculine swimwear from dapperQ:
Ask dapperQ: Masculine Swimwear Part II

About dapperQ:
"dapperQ is a visibility project that celebrates the inner and outer beauty of masculine-presenting lesbians, gender-nonconformists and genderqueers, and transmasculine individuals of all colors, shapes, and sizes. dapperQ does have a fashion focus. But, more importantly, it serves as a vehicle to explore fashion as a social construct, providing our readers and writers with a safe space to document and discuss how gender role expectations, particularly with respect to gender identity and expression, shape who we are as individuals and as a community" (About)

The fashion presented tends to be expensive (they make a point of promoting small, trans-owned businesses, for example), but there are also tips on more affordable options. And generally, for me it is a place to get some inspiration/new ideas fashion-wise.