I'm on an ASD RWY for a given set of condition
Not quite sure what you mean here .. unless, perhaps ASD-limiting runway.
It still appears that you are trying to mix distances in the one calculation .. (mind you, it is late at night and I might be just a tad thick and not understanding where you are coming from ..)
For a given calculation (ie runway, OAT, W/V etc ...) if you are using BFL then you just calculate the various cases and the worst ( ie lowest weight) gives you the answer
If you have the (AFM) ability to unbalance the calculations (some AFMs don't give you the option so it is BFL whether you like it or not)
(a) you don't necessarily use ALL the TOD/TOR/ASD for the various cases .. some AFMs give you opportunity to calculate each separately (which means you can) while others (most) have a combined method of calculation which restricts the opportunity for playing around with the numbers
(b) by iterating the calculation (doing it repeatedly with variations in the input parameters) you can end up with the best weight for the day. Generally only one of the cases will determined the critical calculation
could you do it on a ad hoc basis
If, by ad hoc, you are looking at the pilot doing the calculations and optimising the RTOW, then that would depend on what data he/she has available (whether simplified ops manual stuff or detailed AFM) ... refer back to the earlier comments if you have suitable data.
Main thing is .. generally it is too long winded for the line pilot to run a full AFM calculation (not to mention plain tedious and boring) .. however, regardless of whether the calculation is AFM, ops manual simplified data .. or just looking up some RTOW tables ... the degree of unbalance (which is the same as saying V1/VR ratio) applies to all the calculation cases simultaneously .. ie you can't have different degrees of unbalance for the TODR, TORR, and ASDR by running the calcs for varying V1/VR as the calculation case varies .. would give inconsistent answers.
Or am I still missing the point which is of concern to you ?