Pedro, "adding a 2nd radial" must not be read as "adding a 2nd radiator", hi.
So the existing 9.15m radiator (without 1:9 unun) with newly 2 radials of 4m each could be used as a vertical, inverted-L or inverted-V.
This antenna would then look very similar to my compact 60-10m vertical (inverted-L or -V) consisting of a 9.10m radiator, 4 radials of 4.20m each, fed through a common mode choke (photos). The antenna base is usually attached to the mast at about 0.5m over ground or, if the mast is fixed to a metallic structure, kept away some meters and fixed on a tent peg. This antenna connected to a KX3/ATU performs very well.