OnLine Purchases with split IRA and outside IRA investment

[Jeffrey A DeAngelis]

Howdy, 

If anyone has invested with funds from a self vested IRA and funds from outside an IRA - for instance, 50/50, how do you manage online purchases and split between the two?

For example. A STR purchased property at $100k and you put $50k towards the purchase with a self funded IRA and $50k outside of the IRA means that incoming rent and outgoing property improvements/upkeep are split 50/50 to stay within IRS compliance. If you purchase a new bed, fence, grill, cabinets or cleaning supplies (or whatever) say on Amazon for the property, you can't split payments with two separate cards for the improvement. Most online sites don't allow multiple cards for transactions. Any workarounds?

Thanks.