Good Afternoon, PKM-25,
Several decades ago, I made some prints on (I think) 30-inch paper. They were probably about 30 x 40, if I recall correctly. My negatives were 4 x 5, and I used a 135mm lens. I moved the enlarger to the edge of the table, clamped it in place, removed the baseboard, and projected onto the floor. My "easel" was a piece of Masonite with the paper taped down to it. A cut-out of the table and removal of the baseboard should accomplish the same thing, provided that nothing such as a table leg intrudes on the space. Size could be adjusted with the enlarger head position or simply with bricks or blocks or ???? to raise or lower whatever you use for an easel. I'd try to use vertical projection if possible, because everything tends to stay aligned more easily that way.