Your best bet is to search digital archives of Dutch libraries (like the Royal Library or university special collections) and niche comic/music forums, as original copies of Reload, Freeload, and D-zone are out of print and not widely digitized. Start by checking the Delpher database (which includes historical Dutch publications) and the Dutch National Library's digital depot; while they may not have these specific magazines, they can guide you to related collections. Also join hobbyist groups on platforms like Reddit, Discord, or specialized comic forums where fans of Rosto's Mind My Gap may have preserved scans or discussions.
Because these magazines were underground or free-distribution in the late 1990s and early 2000s, they were never widely archived commercially. Your search will rely on personal collections and fandom. Contact Dutch comic shops that have been around since then (ask for back issues or owner knowledge), and try reaching out to the Rosto estate or Studio Rosto A.D. directly via their official channels. They may have kept copies or know of collectors.
If you are willing to pay, consider posting a 'wanted' request on secondhand marketplaces like Marktplaats or vintage magazine sites; be clear you want scans, not physical copies, to save on shipping. For transcripts or photos, you could also search web archives (Wayback Machine) for old fan pages or the original 'Mind My Gap' Flash episodes, which might include magazine references.
A key tradeoff: the more obscure the magazine, the more time you may need to invest in serendipitous finds. Be patient and cross-post your request to multiple communities. Do not expect a single repository to hold everything. Good luck.