Well, according to MvR's victory list, his first victory in 1918 was on 12 March.
(Don't know, which victories he had on the Triplane in 1917)
From 12 March until his end he met fighters from the following squads (I only show scouts we have in OFF):
March 12 - No. 64: BrisFit: 62 Sdn, RFC
March 13 - No. 65: Camel: 73 Sqdn, RFC
March 18 - No. 66: Camel: 54 Sqdn, RFC
March 24 - No. 67: S.E.5a: 41 Sqdn, RFC
March 25 - No. 68: Camel: 3 Sqdn, RFC
March 27 - No. 71: Camel: 73 Sqdn, RFC
March 27 - No. 72: BrisFit: possibly 11 Sdn, RFC
March 27 - No. 73: BrisFit: 11 Sdn, RFC
April 6 - No. 76: Camel: 46 Sqdn, RFC
April 7 - No. 77: S.E.5a: possibly 24 Sqdn, RFC
April 7 - No. 78: Camel: 73 Sqdn, RFC
April 20 - No. 79: Camel: 3 Sqdn, RFC
April 20 - No. 80: Camel: 3 Sqdn, RFC
So pick your choice, and much success, my friend!