I'm thinking the board is bad ; because ; the igniter should also have a timer cycle , that shuts off the igniter and the propane if the board doesn't see evidence of flame from it's sensor. If your getting spark all the time and the burner is lit then several of the board's logic functions aren't behaving.
Some RV parts stores can bench test the boards , phone any local parts places to find out.
99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.