I have a question around best practice for handling a recurring fastener scenario in an assembly.

We are using multiple sets of a fastener assembly—which includes the same bolt, nut, and washer. We have modelled it as a sub-assembly. In the main assembly that the fastener set is assembled in, the grip length between the bolt head and washer face varies depending on what we are fixing (thicknesses of cleats etc). I’ve set up the fastener sub-assembly so that, based on the grip length (within the sub assembly), it picks the correct bolt length using an equation. For example, with an M20 bolt and a 20.5mm grip length, add a 30mm allowance and you get 50.5mm—round that up to the next standard size (increments of 5mm), so the bolt part selects a 55mm long configuration.

Here’s the problem:
There’s no clean way (that I’ve found) to make this scalable without headaches.

Option 1 – Configurations for each grip length:
Doable, but a pain. Every time the assembly changes, I’d need to add more configs or select multiple configs. 

Option 2 – Flexible fastener set:
Works okay with just one or two sets, but things fall apart when you have more. Rebuild times go through the roof, and SolidWorks starts to glitch out when multiple instances of the same sub-assembly are flexible with different grip length dimensions. (as its kind of working against each other)

Neither approach really scales well.

Ideally I would like to get option 2 to work as this is the quickest and easiest, however is there any smarter way to handle this? Ideally something that doesn’t kill performance or turn into a config-management nightmare.

See attachments for reference.