If you are specifying the same paths, then FP has priority over SMD (you can see this in the man-page for the set_max_delay command, at the bottom where they list the rules for multiple overlapped exceptions).
BTW, as you should know, min-delays will not get "fixed" unless you issue the "set_fix_hold" command.
This could be dangerous if you have not completely defined all timing reqs to prevent DC from seeing erroneous hold-viols and so on.
Anyway, something like the following should be all you need ...
-> set_max_delay [expr $PER_CLKB+$DLAT_ATOB] -from [get_clocks CLKA] -to [get_clocks CLKB]
-> set_min_delay [expr $DLAT_ATOB] -from [get_clocks CLKA] -to [get_clocks CLKB]
-> set_max_delay [expr $PER_CLKA-$DLAT_ATOB] -to [get_clocks CLKA] -from [get_clocks CLKB]
-> set_min_delay [expr 0-$DLAT_ATOB] -to [get_clocks CLKA] -from [get_clocks CLKB]
Note that variable DLAT_ATOB is the ideal clock latency difference/delta between the two clocks (i.e. DLAT_ATOB = $LAT_CLKA-$LAT_CLKB).
This is needed to subtract-out the effect of latency differences, which could esp. cause you to artificially violate the min-delay.
This example assumes that you wish to apply this constraint to ALL signals that cross between the two clocks in BOTH directions.
You thus should NOT also need a FP between the clocks, because you've already caught all paths with the above commands.
(these are point-to-point *exceptions* to the implicit synchronous setup/hold checks between the two clocks)
However, post-CTS in STA, you could still potentially run into the problems I mentioned before if your final latencies differ by a "large" amount.
In my case, I had to stop checking absolute delays, and instead checked the relative delay-spread like I previously described.
My solution was to write a custom TCL procedure in PrimeTime to extract the delays using get_timing_path, get_attribute (on the points and other attributes of a path-object), perform calculations and compare against receive-domain period, and so on.
(A SolvNet search will find a number of PT TCL routines that you can study and modify to do stuff like this.)