Drastically simplify your product line! I know that you're introducing new technology (RMS-EZ, RAS, etc.), but your product line is just becoming unwieldy. Not only will simplifying your line help you on your end, but it will also help your vendors. It seems like you guys are making a buttload of changes very quickly and you're suffering growing pains as a result of it.
I see the lines like this:
1. HPR RMS+ kits that are delivered with a Long delay. Customers are instructed to purchase a drill or the instructions explain how to do it without an AT drill. This will be a large number of UPC's, but if there's one delay per UPC you'll have improved your current situation.
2. LPR and MPR RMS kits that are delivered with the historical S, M, L delays. These customers can't be expected to drill delays.
3. DMS Certification motors. I'd suggest a 29mm and 38mm L1 option (H135W, H100W), a 38mm and 54mm L2 option (J270W, J250W), and a 76mm L3 option (M1350W). This allows customers to get their cert with an SU motor and then ease into the purchase of a case. Again, single delay to be drilled.
4. DMS Specialty motors. Non-standard burn rates like the H45W, I65W, H550ST, and maybe the L1000W if your margins are good on that.
5. Hobby SU motors with historical S, M, L delays
6. Rocket kits
You have a massive product catalog. Simplification and a continuously updated, externally facing catalog will go a long way. Release a new product, release a new catalog. It doesn't have to be fancy, something like your DMS data sheet would be quite effective.
https://aerotech-rocketry.com/uploads/0144ffc9-bf32-4fae-9f91-7d0cf5ddd0bb_DMS™%20Data%20Sheet%205-12-15%20Small.pdf