I would probably go with Mark IV. It's got this great saturation and upper mid bite I can't get from anything else, and has enough enough bass to keep up with modern sounds but is nowhere near tubby. It's the most versatile and well rounded mode in channel 3 IMO and works great for both rhythms and leads, as opposed to extreme which works better for rhythm and IIC+ which works better for lead.
As for using a V30, no that shouldn't be a problem, as long as you either:
a) leave all channels on 45W or less or
b) use the amp on 90W but be careful as to how loud and how often you crank it.
Even though the amp says "90 watts", what that really means is that the power amp can put out 90 watts before distorting. So the amp isn't really giving 90 watts until the power stage starts clipping, which is at about 11:00 on the master output. If you're still concerned, you can also run the amp in triode and/or variac power, both of which will decrease the power rating.