1 - You can't be מקדש someone with a service, since each fraction of the service is not worth the minimum value needed, a peruta. At the time the "money" is needed it's only a loan, and forgiveness of a loan is not an acceptable act of kedushin. [The rule is "ישנו לשכירות מתחילה ועד סוף", Shulchan Aruch Even HaEzer 38/13.]
2 - Even if you would get around the first issue, there might be a problem of אין שליח לדבר עבירה, you can't make an agent when he will be doing an עבירה. He will be marrying a divorcee without waiting three months after her first marriage [הבחנה]. This is forbidden even when only doing kedushin. (Even Haezer 13) However, if the [דבר עבירה] rule applies to עבירות that are not part of the main service the agent is doing, is a matter of dispute. [See Machneh Efraim, shluchin 9, Imrei Bina , Nedarim 13, etc.]
[3 - I"m wondering if this is a דבר שלא בא לעולם, since kedushin cannot be effective at the time of the man's actions.]