If the rivets are only for show, a simple method is to shorten them so they just protrude thru to the rear (unseen) side, rest the head on a suitable formed anvil and peen it over with a hammer.
This is a photo of the rivets on my traction engine. The LH side is the tender/water tank and the RH side the horn plates.
None of the rivets have been fitted with a press. Most are only aesthetics and for show and have been welded on the rear side. The rivets that are joining the tender and horn plates are threaded like a bolt and have a nut on the rear side, allowing the tender to be removed.
